Treatment of Lyes.—The spent lyes withdrawn from the soap-pans are cooled, and the soap, which has separated during the cooling, is carefully removed and returned to the soap-house for utilisation in the manufacture of brown soap. Spent lyes may vary in their content of glycerol from 3 to 8 per cent., and this depends not only upon the system adopted in the working of the soap-pans, but also upon the materials used. Although, in these days of pure caustic soda, spent lyes are more free from impurities than formerly, the presence of sulphides and sulphites should be carefully avoided, if it is desired to produce good glycerine.

The lyes are transferred to a lead-lined tank of convenient size, and treated with commercial hydrochloric acid and aluminium sulphate, sufficient being added of the former to neutralise the free alkali, and render the liquor faintly acid, and of the latter to completely precipitate the fatty acids. The acid should be run in slowly, and the point when enough has been added, is indicated by blue litmus paper being slightly reddened by the lyes.

The whole is then agitated with air, when a sample taken from the tank and filtered should give a clear filtrate.

Having obtained this clear solution, agitation is stopped, and the contents of the tank passed through a filter press. The scum, which accumulates on the treatment tank, may be transferred to a perforated box suspended over the tank, and the liquor allowed to drain from it. The filtered liquor is now rendered slightly alkaline by the addition of caustic soda or carbonate, and, after filtering, is ready for evaporation.

The acid and alum salt used in the above treatment must be carefully examined for the presence of arsenic, and any deliveries of either article, which contain that impurity, rejected.

Lime, bog ore, and various metallic salts, such as ferric chloride, barium chloride, and copper sulphate have been suggested, and in some instances are used instead of aluminium sulphate, but the latter is generally employed.

Evaporation to Crude Glycerine.—The clear treated lyes, being now free from fatty, resinous, and albuminous matter, and consisting practically of an aqueous solution of common salt (sodium chloride) and glycerine, is converted into crude glycerine by concentration, which eliminates the water and causes most of the salt to be deposited.

This concentration was originally performed in open pans heated by fire or waste combustible gases. In the bottom of each pan was placed a dish in which the salt deposited, and this dish was lifted out periodically by the aid of an overhead crane and the contents emptied and washed. Concentration was continued until the temperature of the liquor was 300 deg. F. (149 deg. C.), when it was allowed to rest before storing.

This liquor on analysis gave 80 per cent. glycerol and from 9 to 10-1/2 per cent. salts (ash); hence the present standard for crude glycerine.

Concentration in open pans has now been superseded by evaporation in vacuo. The subject of the gradual development of the modern efficient evaporating plant from the vacuum pan, originated and successfully applied by Howard in 1813 in the sugar industry, is too lengthy to detail here, suffice it to say that the multiple effects now in vogue possess distinct advantages—the greatest of these being increased efficiency combined with economy.

The present type of evaporator consists of one or more vessels, each fitted with a steam chamber through which are fixed vertical hollow tubes. The steam chamber of the first vessel is heated with direct steam, or with exhaust steam (supplied from the exhaust steam receiver into which passes the waste steam of the factory); the treated lyes circulating through the heated tubes is made to boil at a lower temperature, with the reduced pressure, than is possible by heating in open pans.

The vapour given off by the boiling liquor is conveyed through large pipes into the steam chamber of the second vessel, where its latent heat is utilised in producing evaporation, the pressure being further reduced, as this second vessel is under a greater vacuum than No. 1. Thus we get a "double effect," as the plant consisting of two pans is termed. The vapours discharged from the second vessel during boiling are passed through pipes to the steam chamber of the third vessel (in a "triple effect"), and there being condensed, create a partial vacuum in the second vessel. The third vessel may also be heated by means of live steam. The vapours arising from the last vessel of the evaporating plant, or in the case of a "single effect" from the vessel, are conveyed into a condenser and condensed by injection water, which is drawn off by means of the pump employed for maintaining a vacuum of 28 inches in the vessel.

In the most recent designs of large evaporative installations, the vapours generated from the last vessel are drawn through a device consisting of a number of tubes enclosed in a casing, and the latent heat raises the temperature of the treated lyes proceeding through the tubes to supply the evaporator.

It will thus be observed that the object of multiple effects is to utilise all the available heat in performing the greatest possible amount of work. Special devices are attached to the plant for automatically removing the condensed water from the steam chambers without the loss of useful heat, and as a precaution against splashing over and subsequent loss of glycerine through conveyance to the steam chamber, dash plates and "catch-alls" or "save-alls" of various designs are fitted on each vessel.

In working the plant, the liquor in each vessel is kept at a fairly constant level by judicious feeding from one to the other; the first vessel is, of course, charged with treated lyes. As the liquor acquires a density of 42 deg. Tw. (25 deg. B.) salt begins to deposit, and may be withdrawn into one of the many patented appliances, in which it is freed from glycerine, washed and dried ready for use at the soap pans. Difficulty is sometimes experienced with the tubes becoming choked with salt, thereby diminishing and retarding evaporation. It may be necessary to dissolve the encrusted salt with lyes or water, but with careful working the difficulty can be obviated by washing out with weak lyes after each batch of crude glycerine has been run away, or by increasing the circulation.

It is claimed that by the use of the revolving heater designed by Lewkowitsch, the salting up of tubes is prevented.

The salt having been precipitated and removed, evaporation is continued until a sample taken from the last vessel has a density of 60 deg. Tw. (33.3 B.) at 60 deg. F. (15.5 deg. C.). When this point is reached, the crude glycerine is ready to be withdrawn into a tank, and, after allowing the excess of salt to deposit, may be transferred to the storage tank.

The colour of crude glycerine varies from light brown to dark brown, almost black, and depends largely on the materials used for soap-making. The organic matter present in good crude glycerine is small in amount, often less than 1 per cent.; arsenic, sulphides and sulphites should be absent. Crude glycerine is refined in some cases by the producers themselves; others sell it to firms engaged more particularly in the refined glycerine trade.

Distillation.—Crude glycerine is distilled under vacuum with the aid of superheated steam. The still is heated directly with a coal or coke fire, and in this fire space is the superheater, which consists of a coil of pipes through which high pressure steam from the boiler is superheated.

The distillation is conducted at a temperature of 356 deg.F. (180 deg. C.). To prevent the deposition and burning of salt on the still-bottom during the distillation, a false bottom is supported about 1 foot from the base of the still. With the same object in view, it has been suggested to rotate the contents with an agitator fixed in the still.

Every care is taken that the still does not become overheated; this precaution not only prevents loss of glycerine through carbonisation, but also obviates the production of tarry and other bodies which might affect the colour, taste, and odour of the distilled glycerine. The vacuum to be used will, of course, depend upon the heat of the fire and still, but as a general rule good results are obtained with an 18 inch vacuum.

There are quite a large number of designs for still heads, and "catch-alls," having for their object the prevention of loss of glycerine.

The distillate passes into a row of condensers, to each of which is attached a receptacle or receiver. It is needless to state that the condensing capacity should be in excess of theoretical requirements. The fractions are of varying strengths and quality; that portion, with a density less than 14 deg. Tw. (19.4 deg. B.), is returned to the treated-lyes tank. The other portion of the distillate is concentrated by means of a dry steam coil in a suitable vessel under a 28 inch vacuum.

When sufficiently concentrated the glycerine may be decolorised, if necessary, by treating with 1 per cent. animal charcoal and passing through a filter press, from which it issues as "dynamite glycerine".

The residue in the still, consisting of 50-60 per cent. glycerine and varying proportions of various sodium salts—e.g. acetate, chloride, sulphate, and combinations with non-volatile organic acids—is generally boiled with water and treated with acid.

The tar, which is separated, floats on the surface as the liquor is cooling, and may be removed by ladles, or the whole mixed with waste charcoal, and filtered.

The filtrate is then evaporated, when the volatile organic acids are driven off; the concentrated liquor is finally mixed with crude glycerine which is ready for distillation, or it may be distilled separately.

Distilled Glycerine.—This class of commercial glycerine, although of limited use in various other branches of industry, finds its chief outlet in the manufacture of explosives.

Specifications are usually given in contracts drawn up between buyers and sellers, to which the product must conform.

The chief stipulation for dynamite glycerine is its behaviour in the nitration test. When glycerine is gradually added to a cold mixture of strong nitric and sulphuric acids, it is converted into nitro-glycerine, which separates as an oily layer on the surface of the acid. The more definite and rapid the separation, the more suitable is the glycerine for dynamite-making.

Dynamite glycerine should be free from arsenic, lime, chlorides, and fatty acids, the inorganic matter should not amount to more than 0.1 per cent., and a portion diluted and treated with nitrate of silver solution should give no turbidity or discoloration in ten minutes. The specific gravity should be 1.262 at 15 deg. C. (59 deg. F.) and the colour somewhat yellow.

Chemically pure glycerine or double distilled glycerine is produced by redistilling "once distilled" glycerine. Every care is taken to avoid all fractions which do not withstand the nitrate of silver test. The distillation is very carefully performed under strict supervision.

The distillate is concentrated and after treatment with animal charcoal and filtration should conform to the requirements of the British Pharmacopoeia. These are specified as follows: Specific gravity at 15.5 deg. C., 1.260. It should yield no characteristic reaction with the tests for lead, copper, arsenium, iron, calcium, potassium, sodium, ammonium, chlorides, or sulphates. It should contain no sugars and leave no residue on burning.

Animal Charcoal for Decolorisation.—The application of animal charcoal for decolorising purposes dates back a century, and various are the views that have been propounded to explain its action. Some observers base it upon the physical condition of the so-called carbon present, and no doubt this is an important factor, coupled with the porosity. Others consider that the nitrogen, which is present in all animal charcoal and extremely difficult to remove, is essential to the action. Animal charcoal should be freed from gypsum (sulphate of lime), lest in the burning, sulphur compounds be formed which would pass into the glycerine and contaminate it.

The "char" should be well boiled with water, then carbonate of soda or caustic soda added in sufficient quantity to give an alkaline reaction, and again well boiled. The liquor is withdrawn and the charcoal washed until the washings are no longer alkaline. The charcoal is then separated from the liquor and treated with hydrochloric acid; opinions differ as to the amount of acid to be used. Some contend that phosphate of lime plays such an important part in decolorising that it should not be removed, but it has, however, been demonstrated that this substance after exposure to heat has very little decolorising power.

Animal charcoal boiled with four times its weight of a mixture consisting of equal parts of commercial hydrochloric acid (free from arsenic) and water for twelve hours, then washed free from acid, dried, and burned in closed vessels gives a product possessed of great decolorising power for use with glycerines.

A good animal charcoal will have a dull appearance, and be of a deep colour; it should be used in fine grains and not in the form of a powder.

The charcoal from the filter presses is washed free from glycerine (which is returned to the treated lyes), cleansed from foreign substances by the above treatment and revivified by carefully heating in closed vessels for twelve hours.

Glycerine obtained by other Methods of Saponification.—French saponification or "candle crude" glycerine is the result of concentration of "sweet water" produced in the manufacture of stearine and by the autoclave process. It contains 85-90 per cent. glycerol, possesses a specific gravity of 1.240-1.242, and may be readily distinguished from the soap-crude glycerine by the absence of salt (sodium chloride). This glycerine is easily refined by treatment with charcoal.

The glycerine water resulting from acid saponification methods requires to be rendered alkaline by the addition of lime—the sludge is separated, and the liquor evaporated to crude. The concentration may be performed in two stages—first to a density of 32 deg. Tw. (20 deg. B.), when the calcium sulphate is allowed to deposit, and the separated liquor concentrated to 48 deg. Tw. (28 deg. B.) glycerine, testing 85 per cent. glycerol and upwards.

Yield of Glycerine from Fats and Oils.—The following represent practicable results which should be obtained from the various materials:—

Tallow 9 per cent. of 80 per cent. Glycerol. Cotton-seed oil 10 " Cocoa-nut oil 12 " Palm-kernel oil 18 " Olive oil 10 " Palm oil 6 " Greases (Bone fats) 6-8 "

The materials vary in glycerol content with the methods of preparation; especially is this the case with tallows and greases.

Every care should be taken that the raw materials are fresh and they should be carefully examined to ascertain if any decomposition has taken place in the glycerides—this would be denoted by the presence of an excess of free acidity, and the amount of glycerol obtainable from such a fat would be correspondingly reduced.



CHAPTER X.

ANALYSIS OF RAW MATERIALS, SOAP, AND GLYCERINE.

Fats and Oils—Alkalies and Alkali Salts—Essential Oils—Soap—Lyes—Crude Glycerine.

Raw Materials.—Average figures have already been given in Chapters III. and VIII. for the more important physical and chemical characteristics of fats and oils, also of essential oils; the following is an outline of the processes usually adopted in their determination. For fuller details, text-books dealing exhaustively with the respective subjects should be consulted.

FATS AND OILS.

It is very undesirable that any of these materials should be allowed to enter the soap pan without an analysis having first been made, as the oil may not only have become partially hydrolysed, involving a loss of glycerine, or contain albuminous matter rendering the soap liable to develop rancidity, but actual sophistication may have taken place. Thus a sample of tallow recently examined by the authors contained as much as 40 per cent. of an unsaponifiable wax, which would have led to disaster in the soap pan, had the bulk been used without examination. After observing the appearance, colour, and odour of the sample, noting any characteristic feature, the following physical and chemical data should be determined.

Specific Gravity at 15 deg. C. This may be taken by means of a Westphal balance, or by using a picnometer of either the ordinary gravity bottle shape, with perforated stopper, or the Sprengel U-tube. The picnometer should be calibrated with distilled water at 15 deg. C. The specific gravity of solid fats may be taken at an elevated temperature, preferably that of a boiling water bath.

Free acidity is estimated by weighing out from 2 to 5 grammes of the fat or oil, dissolving in neutral alcohol (purified methylated spirit) with gentle heat, and titrating with a standard aqueous or alcoholic solution of caustic soda or potash, using phenol-phthalein as indicator.

The contents of the flask are well shaken after each addition of alkali, and the reaction is complete when the slight excess of alkali causes a permanent pink coloration with the indicator. The standard alkali may be N/2, N/5, or N/10.

It is usual to calculate the result in terms of oleic acid (1 c.c. N/10 alkali = 0.0282 gramme oleic acid), and express in percentage on the fat or oil.

Example.—1.8976 grammes were taken, and required 5.2 c.c. of N/10 KOH solution for neutralisation.

5.2 x 0.0282 x 100 ————————— = 7.72 per cent. free fatty acids, 1.8976 expressed as oleic acid.

The free acidity is sometimes expressed as acid value, which is the amount of KOH in milligrammes necessary to neutralise the free acid in 1 gramme of fat or oil.

In the above example:—

5.2 x 5.61 ————— = 15.3 acid value. 1.8976

The saponification equivalent is determined by weighing 2-4 grammes of fat or oil into a wide-necked flask (about 250 c.c. capacity), adding 30 c.c. neutral alcohol, and warming under a reflux condenser on a steam or water-bath. When boiling, the flask is disconnected, 50 c.c. of an approximately semi-normal alcoholic potash solution carefully added from a burette, together with a few drops of phenol-phthalein solution, and the boiling under a reflux condenser continued, with frequent agitation, until saponification is complete (usually from 30-60 minutes) which is indicated by the absence of fatty globules. The excess of alkali is titrated with N/1 hydrochloric or sulphuric acid.

The value of the approximately N/2 alkali solution is ascertained by taking 50 c.c. together with 30 c.c. neutral alcohol in a similar flask, boiling for the same length of time as the fat, and titrating with N/1 hydrochloric or sulphuric acid. The "saponification equivalent" is the amount of fat or oil in grammes saponified by 1 equivalent or 56.1 grammes of caustic potash.

Example.—1.8976 grammes fat required 18.95 c.c. N/1 acid to neutralise the unabsorbed alkali.

Fifty c.c. approximately N/2 alcoholic potash solution required 25.6 c.c. N/ acid..

25.6 - 18.95 = 6.65 c.c. N/1 KOH required by fat.

1.8976 x 1000 / 6.65 = 285.3 Saponification Equivalent.

The result of this test is often expressed as the "Saponification Value," which is the number of milligrammes of KOH required for the saponification of 1 gramme of fat. This may be found by dividing 56,100 by the saponification equivalent or by multiplying the number of c.c. of N/1 alkali absorbed, by 56.1 and dividing by the quantity of fat taken. Thus, in the above example:—

6.65 x 56.1 / 1.8976 = 196.6 Saponification Value.

The ester or ether value, or number of milligrammes of KOH required for the saponification of the neutral esters or glycerides in 1 gramme of fat, is represented by the difference between the saponification and acid values. In the example given, the ester value would be 196.6 - 15.3 = 181.3.

Unsaponifiable Matter.—The usual method adopted is to saponify about 5 grammes of the fat or oil with 50 c.c. of approximately N/2 alcoholic potash solution by boiling under a reflux condenser with frequent agitation for about 1 hour. The solution is then evaporated to dryness in a porcelain basin over a steam or water-bath, and the resultant soap dissolved in about 200 c.c. hot water. When sufficiently cool, the soap solution is transferred to a separating funnel, 50 c.c. of ether added, the whole well shaken, and allowed to rest. The ethereal layer is removed to another separator, more ether being added to the aqueous soap solution, and again separated. The two ethereal extracts are then washed with water to deprive them of any soap, separated, transferred to a flask, and the ether distilled off upon a water-bath. The residue, dried in the oven at 100 deg. C. until constant, is the "unsaponifiable matter," which is calculated to per cent. on the oil.

In this method, it is very frequently most difficult to obtain a distinct separation of ether and aqueous soap solution—an intermediate layer of emulsion remaining even after prolonged standing, and various expedients have been recommended to overcome this, such as addition of alcohol (when petroleum ether is used), glycerine, more ether, water, or caustic potash solution, or by rotatory agitation.

A better plan is to proceed as in the method above described as far as dissolving the resulting soap in 200 c.c. water, and then boil for twenty or thirty minutes. Slightly cool and acidify with dilute sulphuric acid (1 to 3), boil until the fatty acids are clear, wash with hot water free from mineral acid, and dry by filtering through a hot water funnel.

Two grammes of the fatty acids are now dissolved in neutral alcohol saturated with some solvent, preferably a light fraction of benzoline, a quantity of the solvent added to take up the unsaponifiable matter, and the whole boiled under a reflux condenser. After cooling, the liquid is titrated with N/2 aqueous KOH solution, using phenol-phthalein as indicator, this figure giving the amount of the total fatty acids present. The whole is then poured into a separating funnel, when separation immediately takes place. The alcoholic layer is withdrawn, the benzoline washed with warm water (about 32 deg. C.) followed by neutral alcohol (previously saturated with the solvent), and transferred to a tared flask, which is attached to a condenser, and the benzoline distilled off. The last traces of solvent remaining in the flask are removed by gently warming in the water-oven, and the flask cooled and weighed, thus giving the amount of unsaponifiable matter.

Constitution of the Unsaponifiable Matter.—Unsaponifiable matter may consist of cholesterol, phytosterol, solid alcohols (cetyl and ceryl alcohols), or hydrocarbons (mineral oil). Cholesterol is frequently found in animal fats, and phytosterol is a very similar substance present in vegetable fats. Solid alcohols occur naturally in sperm oil, but hydrocarbons, which may be generally recognised by the fluorescence or bloom they give to the oil, are not natural constituents of animal or vegetable oils and fats.

The presence of cholesterol and phytosterol may be detected by dissolving a small portion of the unsaponifiable matter in acetic anhydride, and adding a drop of the solution to one drop of 50 per cent. sulphuric acid on a spot plate, when a characteristic blood red to violet coloration is produced. It has been proposed to differentiate between cholesterol and phytosterol by their melting points, but it is more reliable to compare the crystalline forms, the former crystallising in laminae, while the latter forms groups of needle-shaped tufts. Another method is to convert the substance into acetate, and take its melting point, cholesterol acetate melting at 114.3-114.8 deg. C., and phytosterol acetate at 125.6 deg.-137 deg. C.

Additional tests for cholesterol have been recently proposed by Lifschuetz (Ber. Deut. Chem. Ges., 1908, 252-255), and Golodetz (Chem. Zeit., 1908, 160). In that due to the former, which depends on the oxidation of cholesterol to oxycholesterol ester and oxycholesterol, a few milligrammes of the substance are dissolved in 2-3 c.c. glacial acetic acid, a little benzoyl peroxide added, and the solution boiled, after which four drops of strong sulphuric acid are added, when a violet-blue or green colour is produced, if cholesterol is present, the violet colour being due to oxycholesterol ester, the green to oxycholesterol. Two tests are suggested by Golodetz (1) the addition of one or two drops of a reagent consisting of five parts of concentrated sulphuric acid and three parts of formaldehyde solution, which colours cholesterol a blackish-brown, and (2) the addition of one drop of 30 per cent. formaldehyde solution to a solution of the substance in trichloracetic acid, when with cholesterol an intense blue coloration is produced.

Water.—From 5 to 20 grammes of the fat or oil are weighed into a tared porcelain or platinum dish, and stirred with a thermometer, whilst being heated over a gas flame at 100 deg. C. until bubbling or cracking has ceased, and reweighed, the loss in weight representing the water. In cases of spurting a little added alcohol will carry the water off quietly.

To prevent loss by spurting, Davis (J. Amer. Chem. Soc., 23, 487) has suggested that the fat or oil should be added to a previously dried and tared coil of filter paper contained in a stoppered weighing bottle, which is then placed in the oven and dried at 100 deg. C. until constant in weight. Of course, this method is not applicable to oils or fats liable to oxidation on heating.

Dregs, Dirt, Adipose Tissue, Fibre, etc.—From 10 to 15 grammes of the fat are dissolved in petroleum ether with frequent stirring, and passed through a tared filter paper. The residue retained by the filter paper is washed with petroleum ether until free from fat, dried in the water-oven at 100 deg. C. and weighed.

If the amount of residue is large, it may be ignited, and the proportion and nature of the ash determined.

The amount of impurities may also be estimated by Tate's method, which is performed by weighing 5 grammes of fat into a separating funnel, dissolving in ether, and allowing the whole to stand to enable the water to deposit. After six hours' rest the water is withdrawn, the tube of the separator carefully dried, and the ethereal solution filtered through a dried tared filter paper into a tared flask. Well wash the filter with ether, and carefully dry at 100 deg. C. The ether in the flask is recovered, and the flask dried until all ether is expelled, and its weight is constant. The amount of fat in the flask gives the quantity of actual fat in the sample taken; the loss represents the water and other impurities, and these latter may be obtained from the increase of weight of the filter paper.

Starch may be detected by the blue coloration it gives with iodine solution, and confirmed by microscopical examination, or it may be converted into glucose by inversion, and the glucose estimated by means of Fehling's solution.

Iodine Absorption.—This determination shows the amount of iodine absorbed by a fat or oil, and was devised by Huebl, the reagents required being as follows:—

(1) Solution of 25 grammes iodine in 500 c.c. absolute alcohol; (2) solution of 30 grammes mercuric chloride in 500 c.c. absolute alcohol, these two solutions being mixed together and allowed to stand at least twelve hours before use; (3) a freshly prepared 10 per cent. aqueous solution of potassium iodide; and (4) a N/10 solution of sodium thiosulphate, standardised just prior to use by titrating a weighed quantity of resublimed iodine dissolved in potassium iodide solution.

In the actual determination, 0.2 to 0.5 gramme of fat or fatty acids is carefully weighed into a well-fitting stoppered 250 c.c. bottle, dissolved in 10 c.c. chloroform, and 25 c.c. of the Huebl reagent added, the stopper being then moistened with potassium iodide solution and placed firmly in the bottle, which is allowed to stand at rest in a dark place for four hours. A blank experiment is also performed, using the same quantities of chloroform and Huebl reagent, and allowing to stand for the same length of time.

After the expiration of four hours 20 c.c. of 10 per cent. solution of potassium iodide and 150 c.c. water are added to the contents of the bottle, and the excess of iodine titrated with N/10 sodium thiosulphate solution, the whole being well agitated during the titration, which is finished with starch paste as indicator. The blank experiment is titrated in the same manner, and from the amount of thiosulphate required in the blank experiment is deducted the number of c.c. required by the unabsorbed iodine in the other bottle; this figure multiplied by the iodine equivalent of 1 c.c. of the thiosulphate solution and by 100, dividing the product by the weight of fat taken, gives the "Iodine Number".

Example.—1 c.c. of the N/10 sodium thiosulphate solution is found equal to 0.0126 gramme iodine.

0.3187 gramme of fat taken. Blank requires 48.5 c.c. thiosulphate.

Bottle containing oil requires 40.0 c.c. thiosulphate.

48.5 - 40.0 = 8.5, and the iodine absorption of the fat is—

8.5 x 0.0126 x 100 ————————— = 33.6. 0.3187

Wijs showed that by the employment of a solution of iodine monochloride in glacial acetic acid reliable iodine figures are obtained in a much shorter time, thirty minutes being sufficient, and this method is now in much more general use than the Huebl. Wijs' iodine reagent is made by dissolving 13 grammes iodine in 1 litre of glacial acetic acid and passing chlorine into the solution until the iodine is all converted into iodine monochloride. The process is carried out in exactly the same way as with the Huebl solution except that the fat is preferably dissolved in carbon tetrachloride instead of in chloroform.

Bromine absorption has now been almost entirely superseded by the iodine absorption, although there are several good methods. The gravimetric method of Hehner (Analyst, 1895, 49) was employed by one of us for many years with very good results, whilst the bromine-thermal test of Hehner and Mitchell (Analyst, 1895, 146) gives rapid and satisfactory results. More recently MacIlhiney (Jour. Amer. Chem. Soc., 1899, 1084-1089) drew attention to bromine absorption methods and tried to rewaken interest in them.

The Refractive index is sometimes useful for discriminating between various oils and fats, and, in conjunction with other physical and chemical data, affords another means of detecting adulteration.

Where a great number of samples have to be tested expeditiously, the Abbe refractometer or the Zeiss butyro-refractometer may be recommended on account of the ease with which they are manipulated. The most usual temperature of observations is 60 deg. C.

The Titre or setting point of the fatty acids was devised by Dalican, and is generally accepted in the commercial valuation of solid fats as a gauge of firmness, and in the case of tallow has a considerable bearing on the market value.

One ounce of the fat is melted in a shallow porcelain dish, and 30 c.c. of a 25 per cent. caustic soda solution added, together with 50 c.c. of redistilled methylated spirit. The whole is stirred down on the water bath until a pasty soap is obtained, when another 50 c.c. of methylated spirit is added, which redissolves the soap, and the whole again stirred down to a solid soap. This is then dissolved in distilled water, a slight excess of dilute sulphuric acid added to liberate the fatty acids, and the whole warmed until the fatty acids form a clear liquid on the surface. The water beneath the fatty acids is then syphoned off, more distilled water added to wash out any trace of mineral acid remaining, and again syphoned off, this process being repeated until the washings are no longer acid to litmus paper, when the fatty acids are poured on to a dry filter paper, which is inserted in a funnel resting on a beaker, and the latter placed on the water-bath, where it is left until the clear fatty acids have filtered through.

About 10-15 grammes of the pure fatty acids are now transferred to a test tube, 6" x 1", warmed until molten, and the tube introduced through a hole in the cork into a flask or wide-mouthed bottle. A very accurate thermometer, graduated into fifths of a degree Centigrade (previously standardised), is immersed in the fatty acids, so that the bulb is as near the centre as possible, and when the fatty acids just begin to solidify at the bottom of the tube, the thermometer is stirred round slowly. The mercury will descend, and stirring is continued until it ceases to fall further, at which point the thermometer is very carefully observed. It will be found that the temperature will rise rapidly and finally remain stationary for a short time, after which it will again begin to drop until the temperature of the room is reached. The maximum point to which the temperature rises is known as the "titre" of the sample.

ALKALIES AND ALKALI SALTS.

Care should be bestowed upon the sampling of solid caustic soda or potash as the impurities during the solidification always accumulate in the centre of the drum, and an excess of that portion must be avoided or the sample will not be sufficiently representative. The sampling should be performed expeditiously to prevent carbonating, and portions placed in a stoppered bottle. The whole should be slightly broken in a mortar, and bright crystalline portions taken for analysis, using a stoppered weighing bottle.

Caustic Soda and Caustic Potash.—These substances are valued according to the alkali present in the form of caustic (hydrate) and carbonate.

About 2 grammes of the sample are dissolved in 50 c.c. distilled water, and titrated with N/1 sulphuric acid, using phenol-phthalein as indicator, the alkalinity so obtained representing all the caustic alkali and one-half the carbonate, which latter is converted into bicarbonate. One c.c. N/1 acid = 0.031 gramme Na{2}O or 0.040 gramme NaOH and 0.047 gramme K{2}O, or 0.056 gramme KOH.

After this first titration, the second half of the carbonate may be determined in one of two ways, either:—

(1) By adding from 3-5 c.c. of N/10 acid, and well boiling for five minutes to expel carbonic-acid gas, after which the excess of acid is titrated with N/10 soda solution; or

(2) After adding two drops of methyl orange solution, N/10 acid is run in until the solution acquires a faint pink tint.

In the calculation of the caustic alkali, the number of c.c. of acid required in the second titration, divided by 10, is subtracted from that used in the first, and this difference multiplied by 0.031, or 0.047 gives the amount of Na{2}O or K{2}O respectively in the weight of sample taken, whence the percentage may be readily calculated.

The proportion of carbonate is calculated by multiplying the amount of N/10 acid required in the second titration by 2, and then by either 0.0031 or 0.0047 to give the amount of carbonate present, expressed as Na{2}O or K{2}O respectively.

An alternative method is to determine the alkalinity before and after the elimination of carbonate by chloride of barium.

About 7-8 grammes of the sample are dissolved in water, and made up to 100 c.c., and the total alkalinity determined by titrating 20 c.c. with N/1 acid, using methyl orange as indicator. To another 20 c.c. is added barium chloride solution (10 per cent.) until it ceases to give a precipitate, the precipitate allowed to settle, and the clear supernatant liquid decanted off, the precipitate transferred to a filter paper and well washed, and the filtrate titrated with N/1 acid, using phenol-phthalein as indicator. The second titration gives the amount of caustic alkali present, and the difference between the two the proportion of carbonate.

When methyl orange solution is used as indicator, titrations must be carried out cold.

Reference has already been made (p. 39) to the manner in which the alkali percentage is expressed in English degrees in the case of caustic soda.

_Chlorides_ are estimated by titrating the neutral solution with N/10 silver nitrate solution, potassium chromate being used as indicator. One c.c. N/10 AgNO_{3} solution = 0.00585 gramme sodium chloride.

The amount of acid necessary for exact neutralisation having already been ascertained, it is recommended to use the equivalent quantity of N/10 nitric acid to produce the neutral solution.

Sulphides may be tested for, qualitatively, with lead acetate solution.

Aluminates are determined gravimetrically in the usual manner; 2 grammes are dissolved in water, rendered acid with HCl, excess of ammonia added, and the gelatinous precipitate of aluminium hydrate collected on a filter paper, washed, burnt, and weighed.

* * * * *

_Carbonated Alkali (Soda Ash)._—The total or available alkali is, of course, the chief factor to be ascertained, and for this purpose it is convenient to weigh out 3.1 grammes of the sample, dissolve in 50 c.c. water, and titrate with N/1 sulphuric or hydrochloric acid, using methyl orange as indicator. Each c.c. of N/1 acid required represents 1 per cent. Na_{2}O in the sample under examination.

A more complete analysis of soda ash would comprise:—

Insoluble matter, remaining after 10 grammes are dissolved in warm water. This is washed on to a filter-paper, dried, ignited, and weighed.

The filtrate is made up to 200 c.c., and in it may be determined:—

Caustic soda, by titrating with N/1 acid the filtrate resulting from the treatment of 20 c.c. (equal to 1 gramme) with barium chloride solution.

Carbonate.—Titrate 20 c.c. with N/1 acid, and deduct the amount of acid required for the Caustic.

_Chlorides._—Twenty c.c. are exactly neutralised with nitric acid, titrated with N/10 AgNO_{3} solution, using potassium chromate as indicator.

Sulphates.—Twenty c.c. are acidulated with HCl, and the sulphates precipitated with barium chloride; the precipitate is collected on a filter paper, washed, dried, ignited, and weighed, the result being calculated to Na{2}SO{4}.

Sulphides and Sulphites.—The presence of these compounds is denoted by the evolution of sulphuretted hydrogen and sulphurous acid respectively when the sample is acidulated. Sulphides may also be tested for, qualitatively, with lead acetate solution, or test-paper of sodium nitro-prusside.

The total quantity of these compounds may be ascertained by acidulating with acetic acid, and titrating with N/10 iodine solution, using starch paste as indicator. One c.c. N/10 iodine solution = 0.0063 gramme Na{2}SO{3}.

The amount of sulphides may be estimated by titrating the hot soda solution, to which ammonia has been added, with an ammoniacal silver nitrate solution, 1 c.c. of which corresponds to 0.005 gramme Na_{2}S. As the titration proceeds, the precipitate is filtered off, and the addition of ammoniacal silver solution to the filtrate continued until a drop produces only a slight opacity. The presence of chloride, sulphate, hydrate, or carbonate does not interfere with the accuracy of this method. The ammoniacal silver nitrate solution is prepared by dissolving 13.345 grammes of pure silver in pure nitric acid, adding 250 c.c. liquor ammoniae fortis, and diluting to 1 litre.

Carbonate of Potash (Pearl Ash).—The total or available alkali may be estimated by taking 6.9 grammes of the sample, and titrating with N/1 acid directly, or adding 100 c.c. N/1 sulphuric acid, boiling for a few minutes, and titrating the excess of acid with N/1 caustic soda solution, using litmus as indicator. In this case each c.c. N/1 acid required, is equivalent, in the absence of Na{2}CO{3}, to 1 per cent. K{2}CO{3}.

Carbonate of potash may be further examined for the following:—

Moisture.—From 2-3 grammes are heated for thirty minutes in a crucible over a gas flame, and weighed when cold, the loss in weight representing the moisture.

Insoluble residue, remaining after solution in water, filtering and well washing.

_Potassium_ may be determined by precipitation as potassium platino-chloride thus:—Dissolve 0.5 gramme in a small quantity (say 10 c.c.) of water, and carefully acidulate with hydrochloric acid, evaporate the resultant liquor to dryness in a tared platinum basin, and heat the residue gradually to dull redness. Cool in a desicator, weigh, and express the result as "mixed chlorides," _i.e._ chlorides of soda and potash. To the mixed chlorides add 10 c.c. water, and platinic chloride in excess (the quantity may be three times the amount of the mixed chlorides) and evaporate nearly to dryness; add 15 c.c. alcohol and allow to stand three hours covered with a watch-glass, giving the dish a gentle rotatory movement occasionally. The clear liquid is decanted through a tared filter, and the precipitate well washed with alcohol by decantation, and finally transferred to the filter, dried and weighed. From the weight of potassium platino-chloride, K_{2}PtCl_{6}, is calculated the amount of potassium oxide K_{2}O by the use of the factor 94/488.2 or 0.19254.

Chlorides, determined with N/10 silver nitrate solution, and calculated to KCl.

Sulphates, estimated as barium sulphate, and calculated to K{2}SO{4}.

Sodium Carbonate, found by deducting the K{2}CO{3} corresponding to the actual potassium as determined above, from the total alkali.

Iron, precipitated with excess of ammonia, filtered, ignited, and weighed as Fe{2}O{3}.

SODIUM CHLORIDE (COMMON SALT).

This should be examined for the following:—

Actual Chloride, either titrated with N/10 silver nitrate solution, using neutral potassium chromate solution as indicator, or, preferably, estimated gravimetrically as silver chloride by precipitation with silver nitrate solution, the precipitate transferred to a tared filter paper, washed, dried and weighed.

Insoluble matter, remaining on dissolving 5 grammes in water, and filtering. This is washed, dried, ignited and weighed.

Moisture.—5 grammes are weighed into a platinum crucible, and heat gently applied. The temperature is gradually increased to a dull red heat, which is maintained for a few minutes, the dish cooled in a desicator, and weighed.

Sulphates are estimated by precipitation as barium sulphate and calculated to Na{2}SO{4}.

Sodium.—This may be determined by converting the salt into sodium sulphate by the action of concentrated sulphuric acid, igniting to drive off hydrochloric and sulphuric acids, and fusing the mass until constant in weight, weighing finally as Na{2}SO{4}.

POTASSIUM CHLORIDE.

This should be examined, in the same way as sodium chloride, for chloride, insoluble matter, moisture, and sulphate. The potassium may be determined as potassium platino-chloride, as described under carbonate of potash.

SILICATES OF SODA AND POTASH.

The most important determinations for these are total alkali and silica.

Total alkali is estimated by dissolving 2 grammes in distilled water, and titrating when cold, with N/1 acid, using methyl orange as indicator.

_Silica_ may be determined by dissolving 1 gramme in distilled water, rendering the solution acid with HCl, and evaporating to complete dryness on the water-bath, after which the residue is moistened with HCl and again evaporated, this operation being repeated a third time. The residue is then heated to about 150 deg. C., extracted with hot dilute HCl, filtered, thoroughly washed, dried, ignited in a tared platinum crucible, and weighed as SiO_{2}.

ESSENTIAL OILS.

As already stated, these are very liable to adulteration, and an examination of all kinds of oil is desirable, while in the case of the more expensive varieties it should never be omitted.

Specific Gravity.—As with fats and oils, this is usually taken at 15 deg. C., and compared with water at the same temperature. In the case of otto of rose and guaiac wood oil, however, which are solid at this temperature, it is generally observed at 30 deg. C. compared with water at 15 deg. C.

The specific gravity is preferably taken in a bottle or U-tube, but if sufficient of the oil is available and a high degree of accuracy is not necessary, it may be taken either with a Westphal balance, or by means of a hydrometer.

Optical Rotation.—For this purpose a special instrument, known as a polarimeter, is required, details of the construction and use of which would be out of place here. Suffice it to mention that temperature plays an important part in the determination of the optical activity of certain essential oils, notably in the case of lemon and orange oils. For these Gildemeister and Hoffmann give the following corrections:—

Lemon oil, below 20 deg. C. subtract 9' for each degree below, above 20 deg. C. add 8' for each degree above.

Orange oil, below 20 deg. C. subtract 14' for each degree below, above 20 deg. C. add 13' for each degree above.

Refractive Index.—This figure is occasionally useful, and is best determined with an Abbe refractometer, at 20 deg. C.

Solubility in Alcohol.—This is found by running alcohol of the requisite strength from a burette into a measured volume of the oil with constant agitation, until the oil forms a clear solution with the alcohol. Having noted the quantity of alcohol added, it is well to run in a small further quantity of alcohol, and observe whether any opalescence or cloudiness appears.

Acid, ester, and saponification values are determined exactly as described under fats and oils. Instead of expressing the result as saponification value or number, the percentage of ester, calculated in the form of the most important ester present, may be obtained by multiplying the number of c.c. of N/1 alkali absorbed in the saponification by the molecular weight of the ester. Thus, to find the percentage as linalyl acetate, the number of c.c. absorbed would be multiplied by 0.196 and by 100, and divided by the weight of oil taken.

Alcohols.—For the estimation of these, if the oil contains much ester it must first be saponified with alcoholic potash, to liberate the combined alcohols, and after neutralising the excess of alkali with acid, the oil is washed into a separating funnel with water, separated, dried with anhydrous sodium sulphate, and is then ready for the alcohol determination.

If there is only a small quantity of ester present, this preliminary saponification is unnecessary.

The alcohols are estimated by conversion into their acetic esters, which are then saponified with standard alcoholic potash, thereby furnishing a measure of the amount of alcohol esterified.

Ten c.c. of the oil is placed in a flask with an equal volume of acetic anhydride, and 2 grammes of anhydrous sodium acetate, and gently boiled for an hour to an hour and a half. After cooling, water is added, and the contents of the flask heated on the water-bath for fifteen to thirty minutes, after which they are cooled, transferred to a separating funnel, and washed with a brine solution until the washings cease to give an acid reaction with litmus paper. The oil is now dried with anhydrous sodium sulphate, filtered, and 1-2 grammes weighed into a flask and saponified with alcoholic potash as in the determination of ester or saponification value.

The calculation is a little complicated, but an example may perhaps serve to make it clear.

A geranium oil containing 26.9 per cent. of ester, calculated as geranyl tiglate, was acetylated, after saponification, to liberate the combined geraniol, and 2.3825 grammes of the acetylated oil required 9.1 c.c. of N/1 alkali for its saponification.

Now every 196 grammes of geranyl acetate present in the acetylated oil correspond to 154 grammes of geraniol, so that for every 196 grammes of ester now present in the oil, 42 grammes have been added to its weight, and it is therefore necessary to make a deduction from the weight of oil taken for the final saponification to allow for this, and since each c.c. of N/1 alkali absorbed corresponds to 0.196 gramme of geranyl acetate, the amount to be deducted is found by multiplying the number of c.c. absorbed by 0.042 gramme, the formula for the estimation of total alcohols thus becoming in the example given:—

9.1 x 0.154 x 100 Per cent. of geraniol = ——————————— = 70.2 2.3825 - (9.1 x 0.042)

The percentage of combined alcohols can be calculated from the amount of ester found, and by subtracting this from the percentage of total alcohols, that of the free alcohols is obtained.

In the example quoted, the ester corresponds to 17.6 per cent. geraniol, and this, deducted from the total alcohols, gives 52.6 per cent. free alcohols, calculated as geraniol.

This process gives accurate results with geraniol, borneol, and menthol, but with linalol and terpineol the figures obtained are only comparative, a considerable quantity of these alcohols being decomposed during the acetylation. The aldehyde citronellal is converted by acetic anhydride into isopulegol acetate, so that this is also included in the determination of graniol in citronella oil.

Phenols.—These bodies are soluble in alkalies, and may be estimated by measuring 5 c.c. or 10 c.c. of the oil into a Hirschsohn flask (a flask of about 100 c.c. capacity with a long narrow neck holding 10 c.c., graduated in tenths of a c.c.), adding 25 c.c. of a 5 per cent. aqueous caustic potash solution, and warming in the water-bath, then adding another 25 c.c., and after one hour in the water-bath filling the flask with the potash solution until the unabsorbed oil rises into the neck of the flask, the volume of this oil being read off when it has cooled down to the temperature of the laboratory. From the volume of oil dissolved the percentage of phenols is readily calculated.

Aldehydes.—In the estimation of these substances, use is made of their property of combining with sodium bisulphite to form compounds soluble in hot water. From 5-10 c.c. of the oil is measured into a Hirschsohn flask, about 30 c.c. of a hot saturated solution of sodium bisulphite added, and the flask immersed in a boiling water bath, and thoroughly shaken at frequent intervals. Further quantities of the bisulphite solution are gradually added, until, after about one hour, the unabsorbed oil rises into the neck of the flask, where, after cooling, its volume is read off, and the percentage of absorbed oil, or aldehydes, calculated.

In the case of lemon oil, where the proportion of aldehydes, though of great importance, is relatively very small, it is necessary to first concentrate the aldehydes before determining them. For this purpose, 100 c.c. of the oil is placed in a Ladenburg fractional distillation flask, and 90 c.c. distilled off under a pressure of not more than 40 mm., and the residue steam distilled. The oil so obtained is separated from the condensed water, measured, dried, and 5 c.c. assayed for aldehydes either by the process already described, or by the following process devised by Burgess (Analyst, 1904, 78):—

Five c.c. of the oil are placed in the Hirschsohn flask, about 20 c.c. of a saturated solution of neutral sodium sulphite added, together with a few drops of rosolic acid solution as indicator, and the flask placed in a boiling water-bath and continually agitated. The contents of the flask soon become red owing to the liberation of free alkali by the combination of the aldehyde with part of the sodium sulphite, and this coloration is just discharged by the addition of sufficient 10 per cent. acetic-acid solution. The flask is again placed in the water-bath, the shaking continued, and any further alkali liberated neutralised by more acetic acid, the process being continued in this way until no further red colour is produced. The flask is then filled with the sodium sulphite solution, the volume of the cooled unabsorbed oil read off, and the percentage of aldehydes calculated as before.

Solidifying Point, or Congealing Point.—This is of some importance in the examination of anise and fennel oils, and is also useful in the examination of otto of rose. A suitable apparatus may be made by obtaining three test tubes, of different sizes, which will fit one inside the other, and fixing them together in this way through corks. The innermost tube is then filled with the oil, and a sensitive thermometer, similar to that described under the Titre test for fats, suspended with its bulb completely immersed in the oil. With anise and fennel, the oil is cooled down with constant stirring until it just starts crystallising, when the stirring is interrupted, and the maximum temperature to which the mercury rises noted. This is the solidifying point.

In the case of otto of rose, the otto is continually stirred, and the point at which the first crystal is observed is usually regarded as the congealing point.

Melting Point.—This is best determined by melting some of the solid oil, or crystals, and sucking a small quantity up into a capillary tube, which is then attached by a rubber band to the bulb of the thermometer, immersed in a suitable bath (water, glycerine, oil, etc.) and the temperature of the bath gradually raised until the substance in the tube is sufficiently melted to rise to the surface, the temperature at which this takes place being the melting point.

The melting point of otto of rose is usually taken in a similar tube to the setting point, and is considered to be the point at which the last crystal disappears.

Iodine Absorption.—In the authors' opinion, this is of some value in conjunction with other data in judging of the purity of otto of rose. It is determined by Huebl's process as described under Fats and Oils, except that only 0.1 to 0.2 gramme is taken, and instead of 10 c.c. of chloroform, 10 c.c. of pure alcohol are added. The rest of the process is identical.

SOAP.

In the analysis of soap, it is a matter of considerable importance that all the determinations should be made on a uniform and average sample of the soap, otherwise very misleading and unreliable figures are obtained. Soap very rapidly loses its moisture on the surface, while the interior of the bar or cake may be comparatively moist, and the best way is to carefully remove the outer edges and take the portions for analysis from the centre. In the case of a household or unmilled toilet soap, it is imperative that the quantities for analysis should all be weighed out as quickly after each other as possible.

Fatty Acids.—Five grammes of the soap are rapidly weighed into a small beaker, distilled water added, and the beaker heated on the water bath until the soap is dissolved.

A slight excess of mineral acid is now added, and the whole heated until the separated fatty acids are perfectly clear, when they are collected on a tared filter paper, well washed with hot water and dried until constant in weight. The result multiplied by 20 gives the percentage of fatty acids in the sample.

A quicker method, and one which gives accurate results when care is bestowed upon it, is to proceed in the manner described above as far as the decomposition with mineral acid, and to then add 5 or 10 grammes of stearic acid or beeswax to the contents of the beaker and heat until a clear layer of fatty matter collects upon the acid liquor.

Cool the beaker, and when the cake is sufficiently hard, remove it carefully by means of a spatula and dry on a filtering paper, add the portions adhering to the sides of the beaker to the cake, and weigh.

The weight, less the amount of stearic acid or beeswax added, multiplied by 20 gives the percentage of fatty acids.

Care must be taken that the cake does not contain enclosed water.

The results of these methods are returned as fatty acids, but are in reality insoluble fatty acids, the soluble fatty acids being generally disregarded. However in soaps made from cocoa-nut and palm-kernel oils (which contain an appreciable quantity of soluble fatty acids) the acid liquor is shaken with ether, and, after evaporation of the ethereal extract, the amount of fatty matter left is added to the result already obtained as above, or the ether method described below may be advantageously employed.

Where the soap under examination contains mineral matter, the separated fatty acids may be dissolved in ether. This is best performed in an elongated, graduated, stoppered tube, the total volume of the ether, after subsidence, carefully read, and an aliquot part taken and evaporated to dryness in a tared flask, which is placed in the oven at 100 deg. C. until the weight is constant.

In a complete analysis, the figure for fatty acids should be converted into terms of fatty anhydrides by multiplying by the factor 0.9875.

In this test the resin acids contained in the soap are returned as fatty acids, but the former can be estimated, as described later, and deducted from the total.

Total Alkali.—The best method is to incinerate 5 grammes of the soap in a platinum dish, dissolve the residue in water, boil and filter, making the volume of filtrate up to 250 c.c., the solution being reserved for the subsequent determination of salt, silicates, and sulphates, as detailed below.

Fifty c.c. of the solution are titrated with N/1 acid, to methyl orange, and the result expressed in terms of Na_{2}O.

Number of c.c. required x 0.031 x 100 = per cent. Na_{2}O.

The total alkali may also be estimated in the filtrate from the determination of fatty acids, if the acid used for decomposing the soap solution has been measured and its strength known, by titrating back the excess of acid with normal soda solution, when the difference will equal the amount of total alkali in the quantity taken.

The total alkali is usually expressed in the case of hard soaps as Na{2}O, and in soft soaps as K{2}O.

Free caustic alkali is estimated by dissolving 2 grammes of the soap, in neutral pure alcohol, with gentle heat, filtering, well washing the filter with hot neutral spirit, and titrating the filtrate with N/10 acid, to phenol-phthalein.

Number of c.c. required x 0.0031 x 50 = per cent. free alkali Na_{2}O, as caustic.

_Free Carbonated Alkali._—The residue on the filter paper from the above determination is washed with hot water, and the aqueous filtrate titrated with N/10 acid, using methyl orange as indicator. The result is generally expressed in terms of Na_{2}O.

Number of c.c. required x 0.0031 x 50 = per cent. free alkali Na_{2}O, as carbonate.

Free Alkali.—Some analysts determine the alkalinity to phenol-phthalein of the alcoholic soap solution without filtering, and express it as free alkali (caustic, carbonates, or any salt having an alkaline reaction).

Combined Alkali.—The difference between total alkali and free alkali (caustic and carbonate together) represents the alkali combined with fatty acids. This figure may also be directly determined by titrating, with N/2 acid, the alcoholic solution of soap after the free caustic estimation, using lacmoid as indicator.

The potash and soda in soaps may be separated by the method described for the estimation of potassium in Pearl ash (page 126).

The potassium platino-chloride (K_{2}PtCl_{6}) is calculated to potassium chloride (KCl) by using the factor 0.3052, and this figure deducted from the amount of mixed chlorides found, gives the amount of sodium chloride (NaCl), from which the sodium oxide (Na_{2}O) is obtained by multiplying by 0.52991.

The potassium chloride (KCl) is converted into terms of potassium oxide (K_{2}O) by the use of the factor 0.63087.

Salt may be determined in 50 c.c. of the filtered aqueous extract of the incinerated soap, by exactly neutralising with normal acid and titrating with N/10 silver nitrate solution, using a neutral solution of potassium chromate as indicator. The final reaction is more distinctly observed if a little bicarbonate of soda is added to the solution.

Number of c.c. required x 0.00585 x 100 = per cent. of common salt, NaCl.

Chlorides may also be estimated by Volhard's method, the aqueous extract being rendered slightly acid with nitric acid, a measured volume of N/10 silver nitrate solution added, and the excess titrated back with N/10 ammonium thiocyanate solution, using iron alum as indicator.

Silicates.—These are estimated by evaporating 50 c.c. of the filtered extract from the incinerated soap, in a platinum dish with hydrochloric acid twice to complete dryness, heating to 150 deg. C., adding hot water, and filtering through a tared filter paper.

The residue is well washed, ignited, and weighed as SiO_{2}, and from this silica is calculated the sodium silicate.

Sulphates may be determined in the filtrate from the silica estimation by precipitation with barium chloride solution, and weighing the barium sulphate, after filtering, and burning, expressing the result in terms of Na{2}SO{4} by the use of the factor 0.6094.

Moisture.—This is simply estimated by taking a weighed portion in small shavings in a tared dish, and drying in the oven at 105 deg. C. until it ceases to lose weight. From the loss thus found is calculated the moisture percentage.

Free or Uncombined Fat.—This is usually determined by repeated extraction of an aqueous solution of the soap with petroleum ether; the ethereal solution, after washing with water to remove traces of soap, is evaporated to dryness and the residue weighed.

A good method, which can be recommended for employment where many determinations have to be performed, is to dissolve 10 grammes of soap in 50 c.c. neutral alcohol and titrate to phenol-phthalein with N/1 acid. Add 3-5 drops HCl and boil to expel carbonic acid, neutralise with alcoholic KOH solution and add exactly 10 c.c. in excess, boil for fifteen minutes under a reflux condenser and titrate with N/1 acid. The difference between this latter figure and the amount required for a blank test with 10 c.c. alcoholic KOH, denotes the amount of alkali absorbed by the uncombined fat.

Examination of the fatty acids as a guide to the probable composition of the soap:—

From the data obtained by estimating the "titre," iodine number, and saponification equivalent of the mixed fatty and rosin acids, and the rosin content, a fairly good idea of the constitution of the soap may be deduced.

The titre, iodine number, and saponification equivalent are determined in exactly the same manner as described under Fats and Oils.

The presence of rosin may be detected by the Liebermann-Storch reaction, which consists in dissolving a small quantity of the fatty acids in acetic anhydride, and adding to a few drops of this solution 1 drop of 50 per cent. sulphuric acid. A violet coloration is produced with rosin acids. The amount of rosin may be estimated by the method devised by Twitchell (Journ. Soc. Chem. Ind., 1891, 804) which is carried out thus:—

Two grammes of the mixed fatty and rosin acids are dissolved in 20 c.c. absolute alcohol, and dry hydrochloric acid gas passed through until no more is absorbed, the flask being kept cool by means of cold water to prevent the rosin acids being acted upon. The flask, after disconnecting, is allowed to stand one hour to ensure complete combination, when its contents are transferred to a Philips' beaker, well washed out with water so that the volume is increased about five times, and boiled until the acid solution is clear, a fragment of granulated zinc being added to prevent bumping. The heat is removed, and the liquid allowed to cool, when it is poured into a separator, and the beaker thoroughly rinsed out with ether. After shaking, the acid liquor is withdrawn, and the ethereal layer washed with water until free from acid. Fifty c.c. neutral alcohol are added, and the solution titrated with N/1 KOH or NaOH solution, the percentage of rosin being calculated from its combining weight. Twitchell suggests 346 as the combining weight of rosin, but 330 is a closer approximation.

The method may be also carried out gravimetrically, in which case petroleum ether, boiling at 74 deg. C. is used for washing out the beaker into the separator. The acid liquor is run off, and the petroleum ether layer washed first with water and then with a solution of 1/2 gramme KOH and 5 c.c. alcohol in 50 c.c. water, and agitated. The rosin is thus saponified and separated. The resinate solution is withdrawn, acidified, and the resin acids collected, dried and weighed.

Halphen's Reaction.—This is a special test to determine the presence or absence of cotton-seed oil fatty acids in mixtures. Equal parts of the fatty acids, amyl alcohol, and a 1 per cent. solution of sulphur in carbon bisulphide, are heated in a test-tube placed in a water-bath until effervescence ceases, then in boiling brine for one hour or longer when only small quantities are present. The presence of cotton-seed oil is denoted by a pink coloration. The reaction is rendered much more rapid, according to Rupp (Z. Untersuch. Nahr. Genussm., 1907, 13, 74), by heating in a stoppered flask.

Other bodies which it is occasionally necessary to test for or determine in soap include:—

Carbolic acid.—Fifty grammes of the soap are dissolved in water and 20 c.c. of 10 per cent. caustic potash added. The solution is treated with an excess of brine, the supernatant liquor separated, and the precipitate washed with brine, the washings being added to the liquor withdrawn. This is then evaporated to a small bulk, placed in a Muter's graduated tube, and acidified with mineral acid.

The volume of separated phenols is observed and stated in percentage on the soap taken.

Or the alkaline layer may be rendered acid and steam distilled; the distillate is made up to a known volume, and a portion titrated by the Koppeschaar method with standard bromine water.

Glycerine.—Five grammes of soap are dissolved in water, decomposed with dilute sulphuric acid, and the clear fatty acids filtered and washed. The filtrate is neutralised with barium carbonate, evaporated to 50 c.c., and the glycerol estimated by the bichromate method detailed under Crude Glycerine.

Starch or gum may be detected by dissolving the soap in alcohol, filtering, and examining the residue on the filter paper. Starch is readily recognised by the blue coloration it gives with a solution of iodine in potassium iodide.

Sugars are tested for by means of Fehlings' solution, in the liquor separated from the fatty acids, after first boiling with dilute acid to invert any cane sugar.

Mercury will be revealed by a black precipitate produced when sulphuretted hydrogen is added to the liquor separated from the fatty acids, and may be estimated by filtering off this precipitate on a tared Gooch's crucible, which is then dried and weighed.

Borax or borates are tested for in the residue insoluble in alcohol. This is dissolved in water, rendered faintly acid with dilute hydrochloric acid, and a strip of turmeric paper immersed for a few minutes in the liquid. This is then dried in the water-oven, when if any boric acid compound is present, a bright reddish-pink stain is produced on the paper, which is turned blue on moistening with dilute alkali.

The amount of the boric acid radicle may be determined by incinerating 5-10 grammes of soap, extracting with hot dilute acid, filtering, neutralising this solution to methyl orange, and boiling to expel carbon dioxide. After cooling, sufficient pure neutralised glycerine is added to form one-third of the total volume, and the liquid titrated with N/2 caustic soda solution, using phenol-phthalein as indicator. Each c.c. of N/2 NaOH solution corresponds to 0.031 gramme crystallised boric acid, H{3}BO{3} or 0.0477 gramme crystallised borax, Na{2}B{4}O{7}.10H{2}O.

LYES.

The amounts of caustic alkali (if any), carbonated alkali, and salt present are determined in the manner already described under Alkali and Alkali Salts. The glycerol content is ascertained by taking 2.5 grammes, adding lead subacetate solution, and filtering without increasing the bulk more than is absolutely necessary; the solution is concentrated to about 25 c.c., and the oxidation with bichromate and sulphuric acid conducted as described in the examination of Crude Glycerine. The solution, after oxidation, is made up to 250 c.c., and titrated against standard ferrous ammonium sulphate solution, the formula for the calculation being:—

{0.25 - 2.5} Per cent. of glycerol = { —-} x 40 { n }

where n equals the number of c.c. of oxidised lyes required to oxidise the ferrous ammonium sulphate solution.

The estimation of actual glycerol in this is necessarily a matter of considerable importance, and a very large number of processes, which are constantly being added to, have been suggested for the purpose. Hitherto, however, only two methods have been generally adopted, viz. the acetin and the bichromate processes. Unfortunately the results obtained by these do not invariably agree, the latter, which includes all oxidisable matter as glycerol, giving sometimes considerably higher results, and it has been suggested that a determination should be made by both methods, and the average of the two results considered the true value. This involves a considerable amount of time and trouble, and it will generally be found sufficient in a works laboratory to determine the glycerol by one method only in the ordinary course, reserving the other process for use as a check in case of dispute or doubt.

Acetin Method.—This consists in converting the glycerol into its ester with acetic acid, the acetic triglyceride, or triacetin being formed. This is then saponified with a known volume of standard alkali, the excess of which is titrated with acid, and the percentage of glycerol calculated from the amount of alkali absorbed.

From 1 to 1.5 grammes of the glycerine is weighed into a conical flask of about 150 c.c. capacity, 7 or 8 c.c. of acetic anhydride added, together with about 3 grammes of anhydrous sodium acetate, and the whole boiled on a sand-bath under a reflux condenser for one to one and a half hours, after which it is allowed to cool, 50 c.c. water added, and the ester dissolved by shaking, and gently warming, the reflux condenser still being attached as the acetin is very volatile. The solution is then filtered from a white flocculent precipitate, which contains most of the impurities, into a larger conical flask, of some 500-600 c.c. capacity, and after cooling, rendered just neutral to phenol-phthalein by means of N/2 caustic soda solution, the exact point being reached when the solution acquires a reddish-yellow tint; 25 c.c. of a strong caustic soda solution is then added, and the liquid boiled for about fifteen minutes, the excess of alkali being titrated after cooling, with N/1 or N/2 hydrochloric acid. A blank experiment is carried out simultaneously, with another 25 c.c. of the soda solution, and the difference in the amounts of acid required by the two, furnishes a measure of the alkali required to saponify the acetin formed, and hence the amount of glycerol in the crude glycerine may be calculated.

Example.—1.4367 grammes crude glycerine, after treatment with acetic anhydride, and neutralising, was saponified with 25 c.c. of a 10 per cent. caustic soda solution.

The blank experiment required 111.05 c.c. N/1 hydrochloric acid. Flask containing acetin " 75.3 c.c. " " ——- 35.75 c.c. " "

Hence, the acetin formed from the glycerol present in 1.4367 grammes of the crude glycerine required 35.75 c.c. N/1 caustic alkali for its saponification, so that the percentage of glycerol may be calculated from the following formula:—

35.75 x 0.03067 x 100 Per cent. glycerol = ——————————- = 76.3. 1.4367

Bichromate Method.—This process was originally devised by Hehner (Journ. Soc. Chem. Ind., 1889, 4-9), but the modification suggested by Richardson and Jaffe (ibid., 1898, 330) is preferred by the authors, and has been practised by them for several years with perfectly satisfactory results.

Twenty-five grammes of the crude glycerine are weighed out in a beaker, washed into a 250 c.c. stoppered flask, and made up to the graduation mark with water. Twenty-five c.c. of this solution are then measured from a burette into a small beaker, a slight excess of basic lead acetate solution added to precipitate organic matter, the precipitate allowed to settle, and the supernatant liquid poured through a filter paper into another 250 c.c. flask. The precipitate is washed by decantation until the flask is nearly full, then transferred to the filter, and allowed to drain, a few drops of dilute sulphuric acid being added to precipitate the slight excess of basic lead acetate solution, and the contents of the flask made up with water to 250 c.c. This solution is filtered, 20 c.c. measured from a burette into a conical flask of about 150 c.c. capacity, 25 c.c. of a standard potassium bichromate solution containing 74.86 grammes bichromate per litre added, together with 50 c.c. of 50 per cent. sulphuric acid, and the whole placed in a boiling water-bath for one hour, after which it is allowed to cool, diluted with water to 250 c.c., and this solution run in to 20 c.c. of a 3 per cent. ferrous ammonium sulphate solution until the latter is completely oxidised, as shown by no blue coloration being produced when one drop is brought into contact with one drop of a freshly prepared solution of potassium ferricyanide on a spot-plate. The ferrous ammonium sulphate solution is previously standardised by titration with a potassium bichromate solution of one-tenth the above strength, made by diluting 10 c.c. of the strong solution to 100 c.c. with water.

The reaction taking place in the oxidation may be represented by the equation:—

3C_{3}H_{5}(OH)_{3} + 7K_{2}Cr_{2}O_{7} + 28H_{2}SO_{4} = 9CO_{2} + 40H_{2}O + 7K_{2}SO_{4} + 7Cr_{2}(SO_{4})_{3}.

Now the strong potassium bichromate solution above mentioned is of such a strength that 1 c.c. will oxidise 0.01 gramme glycerine, and 20 c.c. of the ferrous ammonium sulphate solution should require about 10 c.c. of the one-tenth strength bichromate in the blank experiment. If it requires more or less than this, then the amount of ferrous ammonium sulphate solution which would require exactly 10 c.c. (corresponding to 0.01 gramme glycerine) is calculated, and the oxidised glycerine solution run into this until oxidation is complete.

The formula for the calculation of the percentage of glycerol then becomes:—

{0.25 -(250 x 0.01)} Per cent. of glycerol = { ————— } x 500, { n }

where n equals the number of c.c. of oxidised glycerine solution required to oxidise the ferrous ammonium sulphate solution.

Example:—

In the blank experiment 20 c.c. ferrous ammonium sulphate solution required 9.8 c.c. one-tenth strength bichromate solution, so that 20.4 c.c. ferrous solution would equal 10 c.c. bichromate.

20.4 c.c. ferrous solution required 27.8 c.c. of oxidised glycerine solution before it ceased to give a blue coloration with potassium ferricyanide. {0.25 - (250 x 0.01)} Therefore, per cent. of glycerol = { ——————} x 500 { 27.8 }

= 80.04 per cent.

Other methods have been suggested for the preliminary purification, e.g., silver oxide, silver carbonate and lead subacetate, and copper sulphate and caustic potash, but the lead subacetate alone with care gives satisfactory results.

Other determinations include those of specific gravity, alkalinity, proportion of salts and chloride, and tests for metals, arsenic, sulphur compounds, sugar, and fatty acids.

Specific gravity is determined at 15 deg. C., and may be taken in specific gravity bottle, or with a Westphal balance or hydrometer It usually ranges from 1.3 to 1.31.

Alkalinity, which is usually sodium carbonate, and may be somewhat considerable if the soap has been grained with caustic alkali, is determined after dilution with water by titrating with N/2 acid, using methyl orange as indicator.

Salts.—These may be determined by gently incinerating 5-6 grammes of the glycerine, extracting the carbonaceous mass with distilled water, filtering, and evaporating the filtrate on the water bath. The dried residue represents the salts in the weight taken.

Chloride of sodium (common salt) may be estimated by dissolving the total salts in water, adding potassium chromate, and titrating with N/10 silver nitrate solution.

Copper, lead, iron, magnesium, and calcium may also be tested for in the salts, by ordinary reactions.

Arsenic is best tested for by the Gutzeit method. About 5 c.c. is placed in a test-tube, a few fragments of granulated zinc free from arsenic, and 10 c.c. dilute hydrochloric acid added, and the mouth of the tube covered with a small filter paper, moistened three successive times with an alcoholic solution of mercury bichloride and dried. After thirty minutes the filter paper is examined, when a yellow stain will be observed if arsenic is present.

Sulphates.—These may be precipitated with barium chloride in acid solution, in the usual way, dried, ignited, and weighed.

Sulphites give with barium chloride a precipitate soluble in hydrochloric acid. If the precipitate is well washed with hot water, and a few drops of iodine solution together with starch paste added, the presence of sulphites is proved by the gradual disappearance of the blue starch-iodine compound first formed.

Thiosulphates are detected by precipitating any sulphite and sulphate with barium chloride, filtering, acidifying, and adding a few drops of potassium permanganate solution, when in the presence of a mere trace of thiosulphate, the solution becomes cloudy.

Sulphides.—Lewkowitsch recommends testing for these by replacing the mercury bichloride with lead acetate paper in the Gutzeit arsenic test. Any sulphide causes a blackening of the lead acetate paper.

Sugars may be tested for both before and after inversion, by boiling with Fehlings' solution, when no reduction should take place, if pure.

Fatty acids are detected by the turbidity they produce when the diluted glycerine is acidified.



CHAPTER XI.

STATISTICS OF THE SOAP INDUSTRY.

Until the year 1853 the amount of soap produced annually in this country was readily obtainable from the official returns collected for the purpose of levying the duty, and the following figures, taken at intervals of ten years for the half century prior to that date, show the steady development of the industry during that period:—

___________ Year. Manufactured. Consumed. Exported. Duty per Ton. __ ___ ___ ___ ___ Cwts. Cwts. Cwts. L 1801 509,980 482,140 26,790 21 1811 678,570 651,780 26,790 21 1821 875,000 839,290 35,710 28 1831 1,098,210 955,360 142,850 28 1841 1,776,790 1,517,860 258,930 14 1851 1,937,500 1,741,070 196,430 14 __ ___ ___ ___ ___

Since the repeal of the soap duty, the revenue from which had reached about L1,000,000 per annum, no accurate means of gauging the production exists, but it is estimated that it has nearly quadrupled during the last fifty-five years, being now some 7,000,000 or 8,000,000 cwt. per annum.

The number of soap manufacturers in the United Kingdom is nearly 300, and the amount of capital invested in the industry is roughly estimated to approach L20,000,000 sterling.

Official figures are still available for the amount and value of soap annually imported and exported to and from the United Kingdom, the returns for the last eight years being:—

_Imports._ _____________ Household. Toilet. Total.[13] ____ ____ ____ Year. Quantity. Value. Quantity. Value. Quantity. Value __ ___ __ ___ __ ___ __ Cwts. L Cwts. L Cwts. L 1900 ... ... ... ... 191,233 244,345 1901 ... ... ... ... 302,555 315,026 1902 ... ... ... ... 361,851 429,300 1903 273,542 284,376 25,749 98,032 462,959 499,407 1904 254,425 268,408 17,962 81,162 383,122 438,966 1905 274,238 279,044 19,631 98,507 473,067 500,430 1906 309,975 311,114 18,554 101,243 399,070 468,086 1907 228,035 263,965 18,244 99,432 504,710 545,385 __ ___ __ ___ __ ___ __

Household and toilet soaps were not given separately prior to 1903.

The imports during the last three years for which complete figures are obtainable, came from the following sources:—

_Household Soap._ ___________ 1904. 1905. 1906. ______ __ __ __ L L L From Netherlands 4,315 3,620 3,368 France 14,339 17,783 24,747 Italy 24,209 18,129 32,972 United States 218,740 235,612 242,294 Other Foreign Countries 6,785 3,873 7,448 __ __ __ Total from Foreign Countries 268,388 279,017 310,829 Total from British Possessions 20 27 285 __ __ __ Total 268,408 279,044 311,114 ______ __ __ __

_Toilet Soap._ ___________ 1904. 1905. 1906. ______ __ __ __ L L L From Germany 3,509 3,516 3,001 Netherlands 5,937 5,773 5,919 Belgium 1,568 1,861 3,145 France 7,120 7,633 5,794 Italy 1,176 255 1,233 United States 59,863 74,516 78,382 Other Foreign Countries 166 147 196 __ __ __ Total from Foreign Countries 79,339 93,701 97,670 Total from British Possessions 1,823 4,411 3,225 __ __ __ Total 81,162 98,112 100,895 ______ __ __ __

Exports.

The exports from the United Kingdom during the past eight years have been as follows:—

Household. Toilet. Total.[14] Year. Quantity. Value. Quantity. Value. Quantity. Value. Cwts. L Cwts. L Cwts. L 1900 ... ... ... ... 874,214 939,510 1901 ... ... ... ... 947,485 999,524 1902 ... ... ... ... 1,051,624 1,126,657 1903 998,995 900,814 38,372 217,928 1,057,164 1,143,661 1904 1,049,022 955,774 40,406 228,574 1,108,174 1,208,712 1905 1,167,976 1,013,837 43,837 248,425 1,230,310 1,284,727 1906 1,131,294 1,009,653 46,364 261,186 1,210,598 1,309,556 1907 1,114,624 1,095,170 50,655 280,186 1,240,805 1,459,113

Household and toilet soaps were not given separately prior to 1903.

The exports for the last three years for which complete figures are available, consisted of the following:—

Household Soap.

-+ 1904. 1905. 1906. + - L L L To Sweden 3,027 2,911 3,677 Norway 4,173 3,921 6,005 Netherlands 39,420 41,197 48,601 Dutch Possessions in the Indian Seas 8,586 10,293 7,746 Belgium 73,996 51,583 7,729 France 11,741 12,222 22,907 Portuguese East Africa 28,987 42,981 40,478 Canary Islands 24,763 27,864 27,579 Italy 2,842 3,187 3,962 Turkey 6,974 7,858 5,897 Egypt 12,110 9,467 12,035 China (exclusive of Hong-Kong and Macao) 49,235 114,156 89,169 United States 3,885 1,975 3,924 Columbia 3,601 501 1,364 Ecuador 3,075 3,096 6,861 Chili 5,972 4,865 9,203 Brazil 35,197 28,198 31,726 Argentine Republic 7,802 8,954 13,084 Other Foreign Countries 40,058 53,914 77,687 - Total to Foreign Countries 365,444 429,143 419,634 - To Channel Islands 5,301 8,328 7,968 Gibraltar 13,272 13,868 12,661 British West Africa Gold Coast 22,598 18,513 23,423 Lagos 7,751 8,032 9,518 Nigerian Protectorate 14,942 15,299 20,951 Cape of Good Hope 158,517 143,750 136,388 Natal 74,848 71,874 46,771 British India Bombay (including Kurachi) 59,406 68,945 77,867 Madras 6,364 6,697 10,355 Bengal, Eastern Bengal and Assam. 26,534 23,087 22,648 Burmah 26,389 35,727 37,103 Straits Settlements and Dependencies 26,516 32,214 39,749 Hong-Kong 14,119 15,153 15,685 British West India Islands 74,069 58,881 67,331 British Guiana 12,661 12,023 11,557 Other British Possessions 47,043 52,303 50,044 - Total to British Possessions 590,330 584,694 590,019 - Total 955,774 1,013,837 1,009,653 - - -

_Toilet Soap._ ___________ 1904. 1905. 1906. ______ __ __ __ L L L To Germany 5,051 6,322 6,620 Belgium 3,730 3,265 3,355 France 7,903 8,988 9,324 Portuguese East Africa 2,215 3,973 4,658 Egypt 2,302 3,350 3,525 China (exclusive of Hong-Kong and Macao) 3,096 3,115 3,645 Japan (including Formosa) 3,300 4,649 3,382 United States 50,043 50,668 52,124 Brazil 1,879 2,241 2,292 Other Foreign Countries 22,002 26,081 29,214 __ __ __ Total to Foreign Countries 101,521 112,652 118,139 __ __ __ To Cape of Good Hope 14,094 14,815 14,988 Natal 8,897 11,913 7,280 British India Bombay (including Kurachi) 24,665 24,672 28,316 Madras 4,333 5,851 6,624 Bengal, Eastern Bengal and Assam 14,129 16,021 15,969 Burmah 3,299 3,400 4,667 Straits Settlements and Dependencies 3,590 5,092 4,798 Ceylon and Dependencies 12,210 11,118 12,854 Australia Western Australia 1,549 1,394 1,137 South Australia, (including Northern Territory) 895 644 637 Victoria 11,989 13,614 12,774 New South Wales 3,920 4,278 4,139 Queensland 957 1,097 1,108 Tasmania 482 315 547 New Zealand 5,093 4,498 5,503 Canada 6,382 6,196 8,185 Other British Possessions 11,069 10,855 13,521 __ __ __ Total to British Possessions 127,053 135,773 143,047 __ __ __ Total 228,574 248,425 261,186 ______ __ __ __

The following statistics extracted from official consular reports, etc., show the extent of the soap industry in other parts of the world.

United States.—According to the Oil, Paint and Drug Report the total production of soap in the United States during 1905, exclusive of soap products to the value of $1,437,118 made in establishments engaged primarily in the manufacture of other products, reached a value of $68,274,700, made up in the following manner:—

- Quantity. Value. - Lbs. $ Hard soaps ... 56,878,486 Tallow soap 846,753,798 32,610,850 Olein soap 29,363,376 1,363,636 Foots soap 85,000,133 3,090,312 Toilet soaps, including medicated, shaving, and other special soaps 130,225,417 9,607,276 Powdered soaps, sold as such 120,624,968 4,358,682 All other soaps 143,390,957 6,097,670 Soft soap 33,613,416 667,064 Special soap articles ... 554,881 -

France.—This country exported common soap during 1906 to the value of L556,000, or L8,000 more than in 1905.

The chief centre of the soap industry is Marseilles, which, with about fifty soap factories, produces annually some 3,000,000 cwts.

Germany imported in 1905 soap and perfumery to the value of L3,032, that exported amounting to L15,364.

In Saxony there are eighty soap factories.

Russia.—There are fifty large soap factories in Russia, the annual output from which is about 2,250,000 cwt.

Roumania.—This country possesses about 230 small and eighteen large soap and candle factories, most of which produce only common soap, there being only one firm—in Bucharest—which makes milled soaps.

Denmark.—In this country there are some 200 small soap factories.

Australia.—According to a Board of Trade report, there were ninety-eight soap and candle factories in Australia in 1905, employing 1,568 hands, and producing 495,036 cwt. of soap.

Queensland.—In 1905 this country contained twenty-one soap and candle works, in which 142 hands were employed, and having an output valued at L86,324.

Hong-Kong.—There are about twenty-four soap factories on this island.

Japan.—A Swiss consular report states that in Japan there are now some fifty soap works, producing about 15,000,000 tablets monthly.

Fiji Islands.—These possess only one soap factory, the output from which is 9 cwt. daily.

The following table, compiled from various consular and other official returns, shows the quantity and value of soap imported into different countries and places during the years 1905-7:—

Household. Toilet. Total. Place and Date. Quantity. Value. Quantity. Value. Quantity. Value. Europe Cyprus, 1905 ... ... ... ... ... L9,983 Iceland, 1906 ... ... ... ... ... L6,423 Switzerland, ... ... ... ... 1,702,800 ... 1906 kilos. ... Turkey ... ... ... ... About ... 1,800,000 ... lb. per annum Africa Algeria, 1906 13,609 L228,640 ... ... ... ... tons Cape Colony, 15,897,800 L145,000 427,600 ... ... ... 1906 lb. lb. Gold Coast, 1906 ... ... ... ... ... L23,987 Lourenco, 357,638 L4,293 36,000 L2,195 ... ... Marques, 1906 lb. lb. Natal, 1906 4,263,000 ... 9,870 ... ... ... lb. lb. Orange River 2,382,000 L23,000 1,748 lb. ... ... ... Colony, 1906 lb. Pemba, 1905 ... ... ... ... ... L1,092 Rhodesia, 1906 257,600 ... 2,909 lb. ... ... ... lb. Southern Nigeria, 1905 ... ... ... ... ... L11,990 Tangier ... ... ... ... ... L4,554 Transvaal, 1906 4,407,000 L81,000 202,200 ... ... ... lb. lb. Tripoli, 1905 ... ... ... ... ... L6,080 Tunis, 1906 ... ... ... ... 1,539 L23,727 tons Zanzibar, 1906 ... ... ... ... ... L6,102 America Bahia, 1906 ... ... ... ... 1,031 606,046 tons milreis Brazil, 1906 ... ... ... ... 1,782 ... tons from U.K. British Guiana, 1906-7 ... ... ... ... ... L13,733 Canada, 1906-7 ... ... ... ... ... $600,999 Columbia, 1906 Cartagena ... ... ... ... 65,991 ... tons Barranquilla ... ... ... ... 814,671 $14,712 lb. Costa Rica, 1906 ... ... ... ... ... L1,269 from U.K. Ecuador, 1904 ... ... ... ... 759,034 ... kilos. Granada, 1905 ... ... ... ... ... L3,867 Guatemala, 1906 ... L900 ... ... ... ... Martinique, 1906 693,269 L6,955 ... ... ... ... kilos. Mexico, 1905-6 ... L5,982 ... ... ... ... San Domingo, ... ... ... ... 754,587 1906 lb. ... St. Vincent, 1905-6 ... ... ... ... ... L1,375 Surinam, 1906 ... L3,905 1,142 ... ... ... tons Trinidad, 1906-7 ... ... ... ... ... L29,967 United States, 1905 ... $399,797 ... $1,071,446 ... $1,471,243