 |
In organic as in inorganic chemistry, atoms are bound together by chemical affinity, though it was formerly supposed that an additional or vital force was instrumental in forming organic compounds. For this reason none of these substances, it was thought, could be built up in the laboratory, although many had been analyzed. In 1828 the first organic compound, urea, was artificially prepared, and since then thousands have been synthesized. They are not necessarily manufactured from organic products, but can be made from mineral matter.
296. Molecular Differences.—Molecules may differ in three ways: (1) In the kind of atoms they contain. Compare CO2 and CS2. (2) In the number of atoms. Compare CO and CO2. (3) In the arrangement of atoms, i.e. the molecular structure. Ethyl alcohol and methyl ether have the same number of the same elements, C2H6O, but their molecular structure is not the same, and hence their properties differ.
Qualitative analysis shows what elements enter into a compound; quantitative analysis shows the proportion of these elements; structural analysis exhibits molecular structure, and is the branch to which organic chemists are now giving particular attention. '
A specialist often works for years to synthesize a series of compounds in the laboratory.
297. Sources.—Some organic products are now made in a purer and cheaper form than Nature herself prepares them. Alizarine, the coloring principle of madder, was until lately obtained only from the root of the madder plant; now it is almost wholly manufactured from coal-tar, and the manufactured article serves its purpose much better than the native product. Ten million dollars' worth is annually made, and Holland, the home of the plant, is giving up madder culture. Artificial naphthol-scarlet is abolishing the culture of the cochineal insect. Indigo has also been synthesized. Certain compounds have been predicted from a theoretical molecular structure, then made, and afterwards found to exist in plants. Others are made that have no known natural existence. The source of a large number of artificial organic products is coal-tar, from bituminous coal. Saccharine, a compound with two hundred and eighty times the sweetening power of sugar, is one of its latest products. Wood, bones, and various fermentable liquids are other sources of organic compounds.
298. Marsh-Gas Series.—The chemistry of the hydro-carbons depends on the valence of C, which, in most cases, is a tetrad. Take successively 1, 2, and 3 C atoms, saturate with H, and note the graphic symbols:—
H H H H H H H-C-H, or CH4. H-C-C-H, or? H-C-C-C-H, or ? H H H H H H
Write the graphic and common symbols for 4, 5, and 6 C atoms, saturated with H. Notice that the H atoms are found by doubling the C atoms and adding 2. Hence the general formula for this series would be CnH2n+2. Write the common symbol for C and H with ten atoms of C; twelve atoms; thirteen. This series is called the marsh-gas series. The first member, CH4 methane, or marsh gas, may be written CH3H, methyl hydride, CH3 being the methyl radical. C2H6, ethane, the second one, is ethyl hydride, C2H5H. Theoretically this series extends without limit; practically it ends with C35H72.
In each successive compound of the following list, the C atoms increase by unity. Give the symbols and names of the compounds, and commit the latter to memory:—
Boiling-point. 1. CH4 methane, or CH3H, methyl hydride, gas. 2. C2H6 ethane, C2H5H, ethyl hydride, gas 3. C3H8 propane, C3H7H, propyl hydride, gas 4. ? butane, ? ? 1 degree 5. ? pentane ? ? 38 degrees 6. ? hexane, ? ? 70 degrees 7. ? heptane, ? ? 98 degrees 8. ? octane, ? ? 125 degrees 9. ? nonane, ? ? 148 degrees 10.? dekane, ? ? 171 degrees
Note a successive increase of the boiling-point of the compounds. Crude petroleum contains these hydro-carbons up to 10. Petroleumissues from the earth, and is separated into the different oils by fractional distillation and subsequent treatment with H2SO4, etc. Rhigoline is mostly 5 and 6; gasoline, 6 and 7; benzine, 7; naphtha, 7 and 8; kerosene, 9 and 10. Below 10 the compounds are solids. None of those named, however, are pure compounds. Explosions of kerosene are caused by the presence of the lighter hydro-carbons, as naphtha, etc. Notice that, in going down the list, the proportion of C to H becomes much greater, and the lower compounds are the heavy hydro-carbons. To them belong vaseline, paraffine, asphaltum, etc.
299. Alcohols.—The following replacements will show how the symbols for alcohols, ethers, etc., are derived from those of the marsh-gas series. Notice that these symbols also exhibit the molecular structure of the compound. In CH3H by replacing the last H with the radical OH, we have CH3OH, methyl hydrate. By a like replacement C2H5H becomes C2H5OH, ethyl hydrate. These hydrates are alcohols, and are known as methyl alcohol, ethyl alcohol, etc. The common variety is C2H5OH. How does this symbol differ from that for water, HOH? Notice in the former the union of a positive, and also of a negative, radical.
Complete the table below, making a series of alcohols, by substitutions as above from the previous table.
1. CH3OH, methyl hydrate, or methyl alcohol. 2. C2H5OH, ethyl hydrate, or ethyl alcohol. 3. ? ? ? 4. ? ? ? 5. ? ? ?
Continue in like manner to 10.
The graphic symbol for CH3OH is—-
H H-C-OH; H
for C2H5OH it is—
H H H-C-C-OH. H H
Write it for the next two.
300. Ethers.—Another interesting class of compounds are the oxides of the marsh-gas series. In this series, O replaces H. CH3H becomes (CH3)2O, and C2H5H becomes (C2H5)2O. Why is a double radical taken? These oxides are ethers, common or sulphuric ether being (C2H5)2O. Complete this table, by substituting O in place of H, in the table on page 176.
1. (CH3)2O, methyl oxide, or methyl ether. 2. (C2H5)2O, ethyl oxide, or ethyl ether. 3. ? ? ? 4. ? ? ? 5, etc. ? ? ?
Graphically represented the first two are:—
H H H H H H (1) H-C-O-C-H. (2) H-C-C-O-C-C-H. H H H H H H
301. Substitutions.—A large number of other substitutions can be made in each symbol, thus giving rise to as many different compounds.
In CH4, by substituting 3 Cl for 3 H,—
H Cl H-C-H becomes H-C-CI, or CHCl3,the symbol for chloroform. H Cl
Replace successively one, two, and four atoms with Cl, and write the common symbols. Make the same changes with Br. For each atom of H in CH4 substitute the radical CH3, giving the graphic and common formulae. Also substitute C2H5. Are these radicals positive or negative? From the above series of formulae, of which CH4 is the basis, are derived, in addition to the alcohols and ethers, the natural oils, fatty acids, etc.
302. Olefines.—A second series of hydro-carbons is represented by the general formula CnH2n. The first member of this series is C2H4 or, graphically,—
H H C = C. H H
Compare it with that for C2H6, in the first series, noting the apparent molecular structure of each.
H H C = C - C - H, or C3H6 is the second member. H H H
Write formulae for the third and fourth members.
Write the common formulae for the first ten of this series. This is the olefiant-gas series, and to it belong oxalic and tartaric acids, glycerin, and a vast number of other compounds, many of which are derived by replacements.
303. Other Series.—In addition to the two series of hydro- carbons above given, CnH2n+2 and CnH2n, other series are known with the general formulm CnH2n-2, CnH2n-4, CnH2n-6, CnH2n-8, etc., as far as CnH2n-32, or C26H2O. Each of these has a large number of representatives, as was found in the marsh-gas series. Not far from two hundred direct compounds of C and H are known, not to mention substitutions. The formula CnH2n-6 represents a large and interesting group of compounds, called the benzine series. This is the basis of the aniline dyes, and of many perfumes and flavors.
Chapter LV.
ILLUMINATING GAS.
304. Source.—The three main elements in combustion are O, H, C. Air supplies O, the supporter; C and H are usually united, as hydro-carbons, in luminants and combustibles. H gives little light in burning; C gives much. The fibers of plants contain hydro-carbons, and by destructive distillation these are separated, as gases, from wood and coal, and used for illuminating purposes. Mineral coal is fossilized vegetable matter; anthracite has had most of the volatile hydro-carbons removed by distillation in the earth; bituminous and cannel coals retain them. These latter coals are distilled, and furnish us illuminating gas.
Experiment 129.—Put into a t.t. 20 g. of cannel coal in fine pieces. Heat, and collect the gas over H2O. Test its combustibility. Notice any impurities, such as tar, adhering to the sides of the t.t., or of the receiver after combustion. Try to ignite a piece of cannel coal by holding it in a Bunsen flame. Is it the C which burns, or the hydrocarbons? Distil some wood shavings in a small ignition-tube, and light the escaping gas.
305. Preparation and Purification.—To make illuminating gas, fire-clay retorts filled with coal are heated to 1100 degrees or more, over a fire of coke or coal. Tubes lead the distilled gas into a horizontal pipe, called the hydraulic main, partly filled with water, into which the ends of the gas-pipe dip. The gas then passes through condensers consisting of several hundred feet of vertical pipe, through high towers, called washers, in which a fine spray Fig. 60. Gas Works.
A, furnace; C, retorts containing coal; T, gas-tubes leading to B, the hydraulic main; D, condensers; O, washers, with a spray of water, and sometimes coke; M, purifiers-ferric oxide or lime; G, gas-holder. In C remain the coke and gas carbon. At B, D, E, and O, coal tar, H2O, NH3, CO2, and SO2 are removed. At M are taken out H2S and CO2.of water falls, into chambers with shelves containing the purifiers CaO or hydrated Fe2O3, and finally into a gas-holder, whence it is distributed. At the hydraulic main, condensers, washers, and purifiers, certain impurities are removed froth the gas. Coke is the solid C residue after distillation. Gas-carbon, also a solid, is formed by the separation of the heavier hydro-carbons at high temperature, and is deposited on the sides of the retort.
Coal gas, as it leaves the retort, has many impurities. It is accompanied with about 3 its weight of coal tar, 1/2 its weight of H2O vapor, 1/50 NH3, 1/20 CO2, 1/20 to 1/50 H2S, 1/300 to 1/600 S in other forms. The tar is mostly taken out at the hydraulic main, which also withdraws some H2O with other impurities in solution. The condensers remove the rest of the tar, and the H2O, except what is necessary to saturate the gas. At the main, the condensers, and the washers, NH3 is abstracted, CO2 and H2S are much reduced, and the other S compounds are diminished. Lime purification removes CO2 and H2S, and, to some extent, other S compounds. Iron purification removes H2S. Fe2O3 + 3 H2S = 2 FeS + S + 3 H2O.
The FeS is revivified by exposure to the air. 2 FeS + O3 = Fe2O3 + 2S. It can then be used again. H2S, if not separated, burns with the gas, forming H2S03, which oxidizes in the air to H2SO4; hence the need of removing it. CO2 diminishes the illuminating power.
306. Composition.—Even when freed from its impurities coal-gas is a very complex mixture, the chief components being nearly as follows:—
Percent Diluents, having little C, give H 45) very little light. Notice the small CH, 41) diluents. percentage of luminants, or light- CO 5 ) giving compounds, also the proportion C,HB 1.3) of C to H in them. C,H6 1.2)luminants. CZH4 2.5) Cannel coal contains more of C02 2) impurities. the heavy bydro-carbons, CnH2n, N, etc. 2) etc., than the ordinary bituminous 100 coal. Ten per cent of the coal should be cannel; naphtha is, however, often employed to subserve the same purpose, one ton of ordinary bituminous coal requiring four gallons of oil.
In Boston, 7,000,000 cubic feet of gas have been burned in one day, consuming 500 tons of coal; the average is not more than half that quantity. Of the other products, coke is employed for heating purposes, gas carbon is used to some extent in electrical work, and coal-tar is the source of very many artificial products that were formerly only of natural origin. NH3, is the main source of ammonium salts, and S is made into H2SO4.
307. Natural Gas occurs near Pittsburg, Pa., and in many other places, in immense quantities. It is not only employed to light the streets and houses, but is used for fires and in iron and glass manufactories. It is estimated that 600,000,000 cubic feet are burned, saving 10,000 tons of coal daily in Pittsburg, Only half a dozen factories now use coal. More than half the gas is wasted through safety valves, on account of the great pressure on the pipes as it issues from the earth.
These reservoirs of natural gas very frequently occur in sandstone, usually in the vicinity of coal-beds, but sometimes remote from them. In all cases the origin of the gas is thought to be in the destructive distillation, extending through long geological periods, of coal or of other vegetable or animal matter in the earth's interior.
Natural gas varies in composition, and even in the same well, from day to day; it consists chiefly of CH4, with some other hydro-carbons.
CHAPTER LVI.
ALCOHOL.
308. Fermented Liquor.
Experiment 130.—Introduce 20 cc.of molasses into a flask of 200 cc, fill it with water to the neck, and put in half a cake of yeast. Fit to this a d.t., and pass the end of it into a t.t. holding a clear solution of lime water. Leave in a warm place for two or three days. Then look for a turbidity in the lime water, and account for it. See whether the liquid in the flask is sweet. The sugar should be changed to alcohol and CO2. This is fermented liquor; it contains a small percentage of alcohol.
309. Distilled Liquor. Experiment 131.—Attach the flask used in the last experiment to the apparatus for distilling water (Fig. 32), and distil not more than one-fifth of the liquid, leaving the rest in the flask. The greater part of the alcohol will pass over. To obtain it all, at least half of the liquid must be distilled; what passes over towards the last is mostly water. Taste and smell the distillate. Put some into an e.d. and touch a lighted match to it. If it does not burn, redistil half of the distillate and try to ignite the product. Try the combustibility of commercial alcohol; of Jamaica ginger, or of any other liquid known to contain alcohol.
310. Effect on the System.
Experiment 132.—Put a little of the white of egg into an e.d. or a beaker; cover it with strong alcohol and note the effect. Strong alcohol has the same coagulating action on the brain and on the tissues generally, when taken into the system, absorbing water from them, hardening them, and contracting them in bulk.
311. Affinity for Water.
Experiment 133.—To show the contraction in mixing alcohol and water, measure exactly 5cc.of alcohol and 5cc.of water. Pour them together, and presently measure the mixture. The volume is diminished. A strip of parchment soaked in water till it is limp, then dipped into strong alcohol, becomes again stiff, owing to the attraction of alcohol for water.
312. Purity.—The most important alcohols are methyl alcohol and ethyl alcohol. The former, wood spirit, is obtained in an impure state by distilling wood; it is used to dissolve resins, fats, oils, etc., and to make aniline. It is poisonous, as are the others.
Ethyl alcohol, spirit of wine, is the commercial article. It is prepared by fermenting glucose, and distilling the product. It boils at 78 degrees, vaporizing 22 degrees lower than water, from which it can be separated by fractional distillation. By successive distillations of alcohol ninety-four per cent can be obtained, which is the best commercial article, though most grades fall far below this. Five per cent more can be removed by distilling with CaO, which has a strong affinity for water. The last one per cent is removed by BaO. One hundred per cent constitutes absolute alcohol, which is a deadly poison. Diluted, it increases the circulation, stimulates the system, hardens the tissues by withdrawing water, and is the intoxicating principle in all liquors.—It is very inflammable, giving little light, and much heat, and readily evaporates.
Beer has usually three to six per cent of alcohol; wines, eight to twenty per cent. The courts now regard all liquors having three per cent, or less, of alcohol, as not intoxicating. In Massachusetts it is one per cent.
CHAPTER LVII.
OILS, FATS, AND SOAPS.
313. Sources and Kinds of Oils and Fats.—Oils and fats are insoluble in water; the former are liquid, the latter solid. Most fats are obtained from animals, oils from both plants and animals. Oils are classified as fixed and essential. Castor oil is an example of the former and oil of cloves of the latter. Fixed oils include drying and non-drying oils. They leave a stain on paper, while essential, or volatile oils, leave no trace, but evaporate readily. Essential oils dissolved in alcohol furnish essences. They are obtained by distilling with water the leaves, petals, etc., of plants. Drying oils, as linseed, absorb O from the air, and thus solidify. Non-drying ones, as olive, do not solidify, but develop acids and become rancid after some time.
Oils and fats are salts of fatty acids and the base glycerin. The three most common of these salts are olein, found in olive oil, palmitin, in palm oil and human fat, and stearin, in lard. The first is liquid, the second semi-solid, the last solid. Most fats are mixtures of these and other salts.
Olefin = Glyceryl) ( oleic) oleate ) ( ) Pahnitin = Glyceryl)salts from (palmitic)acid and glyceryl hydrate. palmitate) ( ) Stearin = Glyceryl) (stearic ) stearate)
314. Saponification consists in separating these salts into their acids and the base glycerin; soap-making is the best illustration. To effect this separation, a strong soluble base is used, KOH for soft, and NaOH for hard soap. Study this reaction:
Glyceryl oleate ) (sodium ) (oleate ) Glyceryl palmitate) + (hydrate) = sodium (palmitate) + (glyceryl Glyceryl stearate ) (stearate ) (hydrate
Soaps are thus salts of fatty acids and of K or Na.
315. Soap is soluble in soft water, but the sodium stearate probably unites with water to form hydrogen sodium stearate and NaOH. The grease which exudes from the skin, or appears in fabrics to be washed, is attacked by this NaOH and removed, together with the suspended dirt, and a new soap is formed and dissolved in the water. Hard water contains salts of Ca and Mg, and when soap is used with it the Na is at once replaced by these metals, and insoluble Ca or Mg soaps are formed. Hence in hard water soap will not cleanse till all the Ca and Mg compounds have combined.
316. Glycerin, C3H5(OH)3, is a sweet, thick, colorless, unctuous liquid, used in cosmetics, unguents, pomades, etc. It is prepared in quantity by passing superheated steam over fats when under pressure.
317. Dynamite.—Treated with HNO3 and H2SO4 glycerin forms the very explosive and poisonous liquid nitro-glycerin. In this process the C3H5(OH)3 becomes C3H5(NO3)3. C3H5(OH)3 + 3HNO3 = C3H5(NO3)3+3 H2O. H2SO4 is used to absorb the H2O which is formed. Nitro-glycerin, absorbed by gunpowder, diatomaceous earth, sawdust, etc., forms dynamite. For obvious reasons the pupil should not experiment with these substances.
318. Butter and Oleomargarine.—Milk contains minute particles of fat, about 1/500 of an inch in diameter, which give it the whitecolor. These particles are lighter than the containing liquid, and rise to the top as cream. Churning unites the particles more closely, and separates them from the buttermilk. The flavor of butter is due to the presence of five or ten per cent of butyric and other acids of the same series.
It was found that cows gave milk after they ceased to have food; hence it was inferred that the milk was produced at the expense of the cows' fat. Why could not butter be artificially made from the same fat? It was but a step from fat to milk, as it was from milk to butter. Oleomargarine, or butterine, was the result. Beef fat, suet, is washed in water, ground to a pulp, and partially melted and strained, the stearin is separated from the filtered liquid and made into soap, and an oily liquid is left. This is salted, colored with annotto, mixed with a certain portion of milk, and churned. The product is scarcely distinguishable from butter, and is chemically nearly identical with it, though less likely to become rancid from the absence of certain fatty acids; its cost is perhaps one-third as much as that of butter.
Chapter LVIII
CARBO-HYDRATES.
319. Carbon and Water.—Some very important organic compounds have H and O, in the proper proportion to form water, united with C. The three leading ones are sugar, C12H22O11 or C12(H2O)11, starch, C6H10O6, or ?, and cellulose, C18H30O15 or ?. Note the significance of the name carbo-hydrates as applied to them.
320. Sugars may be divided into two classes,—the sucroses, C12H22O11, and the glucoses, C6H12O6. Sucrose, the principal member of the first class, is obtained from the juice of the maple, the palm, the beet and the sugarcane; in Europe largely from the beet, in America from cane. Granulated sugar is that which has been refined; brown sugar is the unrefined. From the sap evaporated by boiling, brown sugar crystallizes, leaving molasses, which contains glucose and other substances. Good molasses has but a small percentage of glucose. To refine brown sugar it is dissolved in water, a small quantity of blood is added to remove certain vegetable substances, after which it is filtered through animal charcoal, i.e. bone-black, a process which takes out the coloring-matter. The water is then evaporated in vacuum-pans, so as to boil at about 74 degrees and to prevent conversion into grape sugar. By this process much glucose or syrup is formed, which is separated from the crystalline sucrose by rapidly revolving centrifugal machines. Great quantities of sucrose are used for food by all civilized nations. A single refinery in New York purifies 2,000,000 pounds per day.
321. Glucose, or invert sugar, the principal member of the second class, consists of two distinct kinds of sugar, —dextrose and levulose. These differ in certain properties, but have the same symbol. Both are found in equal parts in ripe fruits, while sucrose occurs in the unripe. Honey contains these three kinds of sugar.
Sucrose, by the action of heat, weak acids, or ferments, may be resolved into the other two varieties. C12H22O11 + H2O = C6H12O6 + C6H12O6. No mode of reversing this process, or of transforming glucose into sucrose is known. Glucose is easily made from starch or from the cellulose in cotton rags, sawdust, etc. If boiled with dilute H2SO4 starch takes up water and becomes glucose. C6H10O5 + H2O = C6H12O6.
CaCO3 is added to precipitate the H2SO4, which remains unchanged. State the reaction. The product is filtered and the filtrate is evaporated. Much glucose is made from the starch of corn and potatoes.
322. Starch is found in all plants, especially in grains, seeds, and tubers. Green plants—those containing chlorophyll— manufacture their own starch from CO2 and H2O. These chlorophyll grains are the plant's chemical laboratories, and hundreds of thousands of them exist in every leaf. CO2 and a very little H2O enter the leaf from the air, H2O being also drawn up through the root and stem from the earth. In some unknown way in the leaf, light has the power of synthesizing these into starch and setting free O, which is returned to the atmosphere.6 CO2 + 5 H2O = C6H10O5 + 12 O. As no such change takes place in darkness, all green plants must have light. Parasitic plants, which are usually colorless, obtain starch ready-made from those on which they feed.
323. Uses.—Glucose is used in the manufacture of alcohol and cheap confectionery, and in adulterating sucrose. It is only two- thirds as sweet as the latter. The seeds of all plants contain starch for the germinating sprout to feed upon; but starch is insoluble, and hence useless until it is converted into glucose. This is effected by the action of warmth, moisture, and a ferment in the seed. Glucose is soluble and is at first the plant's main food.
Commercial starch is made in the United States chiefly from corn; in Europe, from potatoes. Differences in the size of starch granules enable microscopists to determine the plant to which they belong.
324. Cellulose, or woody fiber, is the basis of all vegetable cell walls. Cotton fiber represents almost pure cellulose. From it are made paper and woven tissues. In paper manufacture, woody fiber is made into a pulp, washed, bleached, filtered, hot- pressed, and sometimes glazed. Parchment paper, vegetable parchment, is made by dipping unglazed paper for half a minute into cold dilute H2SO4, 1 part H2O, 2 1/2 parts H2SO4, and then washing. The fiber, by chemical change, is thus toughened. The cell walls of wood are impure cellulose; hence the inferior quality of paper made from wood-pulp. Paper is now employed for a large number of purposes for which wood has heretofore been used, such as for barrels, pails, and other hollow ware, wheels, etc.
325. Gun-cotton is made by treating cotton fiber with H2SO4 and HNO3, washing and drying. To all appearances no change has taken place, but the substance has become an explosive compound.
326. Dextrin, a gummy substance used for the backs of postage stamps, is a carbo-hydrate, as in fact are gums in general. Dextrin is made by heating starch with H2SO4 at a lower temperature than for dextrose.
327. Zylonite and Celluloid. -These two similar substances embody the latest use of cellulose in manufactured articles. For zylonite, linen paper is cut into strips two feet by one inch, soaked ten minutes in a mixture of H2SO4 and HNO3, a process called nitration, washed for several hours, then ground to a fine pulp, and thoroughly dried. It is then similar to pyroxiline. Aniline coloring-matter of any desired shade is added, after which it is dissolved by soaking some hours in alcohol and camphor, the liquid is evaporated, and the substance is kneaded between steam-heated iron rollers, dried with hot air, and finally subjected to great pressure, to harden it, and cut into sheets. Zylonite is combustible at a low temperature, and when in the pyroxiline stage, explosively so. Ivory, coral, amber, bone, tortoise shell, malachite, etc., are so closely imitated that the imitation can only be detected by analysis. Collars, combs, canes, piano-keys, and jewelry, are manufactured from it, and it can be made transparent enough for windows.
CHAPTER LIX
CHEMISTRY OF FERMENTATION.
328. Ferments.—A large number of chemical changes are brought about through the direct agency of bodies called ferments; their action is called fermentation. Ferments are sometimes lifeless chemical products found in living bodies; but in other cases they are humble plants.
329. Yeast is one of the most common of living ferments, wild yeast being a microscopic plant found on the ground near apple- trees and grape-vines, and often in the air. The cultivated variety is sold by grocers. The temperature best suited to the rapid multiplication of the germs forming the ferment plant is 25 degrees to 35 degrees.
330. Alcoholic and Acetic Fermentation.—The changes which the juice of the apple undergoes in forming cider and vinegar are a good illustration of fermentation by a living plant. Apple-juice contains sucrose. Yeast germs from the air, getting into this unfermented liquor, cause it to "work." This process changes sucrose to glucose, and glucose to alcohol and CO2, and is known as alcoholic fermentation. The latter reaction, C6H12O6 = 2 C2H6O + 2 CO, is only partially correct, as other products are formed. The juice has now become cider; the sugar alcohol. After a time, if left exposed, another organism finds its way to the alcohol, and transforms it into acetic acid, HC2H8O2, and H2O. This process is called acetic fermentation. C2H6O + O2 = HC2H3O2 + H2O. For this fermentation, a liquor should not have over ten per cent of alcohol. Mother of vinegar consists of the germs that caused the fermentation. Still a third species of ferment may cause another action, changing acetic acid to H2O and CO2. The vinegar then tastes flat. HC2H3O2 + 4 O = 2H2O + 2 CO2.
Some mineral acids, as H2SO4 and HCl, and some organic acids, are regarded as lifeless ferments. To this class are thought to belong the diastase of malt and the pepsin of the stomach. This variety of ferments exists in the seeds of all plants, and changes starch to glucose.
331. Bread which is raised by yeast is fermented, the object being to produce CO2, bubbles of which, with the alcohol, cause the dough to rise and make the bread light.
Grapes and other fruits ferment and produce wines, etc., from which distilled liquors are obtained.
332. Lactic Fermentation changes the sugar of milk, lactose, to lactic acid, i.e. sour milk. In canning fruit, any germs present are killed by heating, and those from the air are excluded by sealing the can. Milk has been kept sweet for years by boiling, and tightly covering the receptacle with two or three folds of cotton cloth.
333. Putrefaction is fermentation in which the products of decay are ill-smelling. Saprophytes attack the dead matter, feed on it, and cause it to putrefy. This action, as well as that of ordinary fermentation, used to be attributed solely to oxygen. Germs bring back organic matter to a more elementary state, and so have a very important function. By some scientists, digestion is regarded as a species of fermentation, probably due to the action of lifeless ferments; e.g. sucrose cannot be taken into the system, but is first fermented to glucose.
334. Most Infectious Diseases are now thought to be due to parasites of various kinds, such as bacteria, microbes, etc., with which the victim often swarms, and which feed on his tissues, multiplying with enormous rapidity. Such diseases are small-pox, intermittent and yellow fevers, etc. Consumption, or tuberculosis, is believed to be caused by a microbe which destroys the lungs. In some diseases not less than fifteen billions of the organisms are estimated to exist in a cubic inch. These multiply so rapidly that from a single germ in forty-eight hours may be produced nearly three hundred billions. These germs do not spring into life spontaneously from inorganic matter, but come from pre-existent similar forms. Parasites are not so rare in the system even of a healthy person as is generally supposed. They are found on our teeth and in many of the tissues of the body.
Several infectious diseases are now warded off or rendered less virulent by vaccination, the philosophy of which is that the organisms are rendered less dangerous by domestication; several crops, or generations, are grown in a prepared liquid, each less injurious than its parent. Some of the more domesticated ones are introduced into the system, and the person has only a modified form of the disease, often scarcely any at all, and is for a more or less limited time insured against further danger.
Dust particles and motes floating in the air are in part germs, living or dead, often requiring only moisture and mild temperature for resuscitation. Most of these are harmless.
Chapter LX.
CHEMISTRY OF LIFE.
335. Growth.—The chemistry of organic life is very complex, and not well understood. A few of the principal points of distinction between the two great classes of living organisms, plants and animals, are all that can be noted here. Minerals grow by accretion, i.e. by the external addition of molecules of the same material as their interior. A crystal of quartz grows by the addition of successive molecules of SiO2, arranged in a symmetrical manner around its axis. The growth of crystals can be seen by suspending a string in a saturated solution of CuSO4, or of sugar. In plants and animals the growth is very much more complex, but is from the interior, and is produced by the multiplication of cells. To produce this cell-growth and multiplication, food-materials must be furnished and assimilated. In plants, sap serves to carry the food-materials to the parts where they are needed. In the higher animals, vari- ous fluids, the most important of which is the blood, serve the same purpose.
336. Chemistry of Plants.—In ultimate analysis, plants consist mainly of C, H, O, N, P, K. In proximate analysis, as it is called, they are found to contain these elements combined to form substances like starch, sugar, etc. Water is the leading compound in both animals and plants. One of the most important differences between animals and plants is, that all plants, except parasitic ones, are capable of building up such compounds as starch from mineral food-stuffs, while animals have not that power, but must have the products of proximate analysis ready prepared, as it were, by the plant. Hence plants thrive on minerals, whereas animals feed on plants or on other animals. The power which plants have of transforming mineral matter is largely due to sunlight, the action of which in separating CO, was described. The reaction in the synthesis of starch from CO2 and H2O in the leaf, is thought to be as follows: 6 CO2 + 5 H2O = C6H10O5 + 12 O. C6H10O5 is taken into the tree as starch; 12 O is given back to the air. All the constituents, except CO2 and a very small quantity of H2O, are absorbed by the roots, from the soil, from which they are soon withdrawn by vegetation. To renew the supply, fertilizers or manures are applied to the soil. These must contain compounds of N, P, and K. N is usually applied in the form of ammonium compounds, e.g. (NH4)2SO4, (NH4)2CO3, and NH4NO3. The reduction and application of Cas(PO4)2 for this purpose was described. K is usually applied in the form of KCl and K2SO4.
337. Food of Man.—In the higher animals the object is not so much to increase the size as to supply the waste of the system. The principal elements in man's body are C, H, O, N, S, P.
An illustration of the transformation of mineral foods by plants before they can be used by animals is found in the Ca3(PO4)2 of bones. This is rendered soluble; plants absorb and transform it; animals eat the plants and obtain the phosphates. Thus man is said to "eat his own bones." The food of mankind may be divided into four classes (1) proteids, which contain C, H, O, N, and often S and P; (2) fats, and (3) amyloids, both of which contain C, H, O; (4) minerals. Examples of the first class are the gluten of flour, the albumen of the white of egg, and the casein of cheese. To the second class belong fats and oils; to the third, starch, sugar, and gums; to the fourth, H2O, NaCl and other salts. Since only proteids contain all the requisite elements, they are essential to human food, and are the only absolutely essential ones, except minerals; but since they do not contain all the elements in the proportion needed by the system, a mixed diet is indispensable. Milk, better than any other single food, supplies the needs of the system. The digestion and assimilation of these food-stuffs and the composition of the various tissues is too complicated to be taken up here; for their discussion the reader is referred to works on physiological chemistry.
338. Conservation.—Plants, in growing, decompose CO2, and thereby store up energy, the energy derived from the light and heat of the sun. When they decay, or are burned, or are eaten by animals, exactly the same amount of energy is liberated, or changed from potential to kinetic, and the same amount of CO2 is restored to the air. The tree that took a hundred years to complete its growth may be burned in an hour, or be many years in decaying; but in either case it gives back to its mother Nature, all the matter and energy that it originally borrowed. The ash from burning plants represents the earthy matter, or salts, which the plant assimilated during its growth; the rest is volatile. In the growth and destruction of plants or of animals, both energy and matter have undergone transformation. Animals, in feeding on plants, transform the energy of sunlight into the energy of vitality. Thus "we are children of the sun."
CHAPTER LXI.
THEORIES.
339. The La Place Theory.—This theory supposes that at one time the earth and the other planets, together with the sun, constituted a single mass of vapor, extending billions of miles in space; that it rotated around its center; that it gradually shrank in volume by the transformation of potential into kinetic energy; that portions of its outer rim were thrown off, and finally condensed into planets; that our sun is only the remainder of that central mass which still rotates and carries the planets around with it; that the earth is a cooling globe; that the other planets are going through the same phases as the earth; and finally that the sun itself is destined like them to become a cold body.
340. A Cooling Earth.—The sun's temperature is variously estimated at many thousands, or even millions o degrees. Many metals which exist on the earth as solids -e.g. iron- are gases in the dense atmosphere of the sun. Thus the earth, in its early existence, must have been composed of gases only, which in after ages condensed into liquids and solids. So intense was the heat at that time, that substances probably existed as elements instead of compounds, i.e. the temperature was above the point of dissociation. We have seen that Al2O3, CaO, SiO2, etc., are dissociated at the highest temperatures only. If the temperature were above that of combination, compounds could not exist as such, but matter would exist in its elemental state. On slowly cooling, these elements would combine. It is, then, a fair inference that such compounds as need the highest temperatures to separate them, as silica, silicates, and some oxides, were formed from their elements at a much earlier stage of the earth's history than were those compounds that are more easily separable, such as water, lead sulphide, etc., and that the most infusible substances were solidified first.
341. Evolution.—As the earth slowly cooled, elements united to form compounds, gases condensed to liquids, and these to solids. At one time the entire surface of our planet may have been liquid. When the cooling surface reached a point somewhat below that of boiling water, the lowest forms of life appeared in the ocean. This was many millions of years ago. Most scientists believe that all vegetable and animal life has developed from the lowest forms of life. There is also a theory that all chemical elements are derivatives of hydrogen, or of some other element, and that all the so-called elements are really compounds, which a sufficiently high temperature would dissociate. As evidence of this, it is said that less than half as many elements have been discovered in the sun as in the earth, and that comets and nebula, which are less developed forms of matter than the sun, have a few simple substances only.
It is easy to fancy that all living bodies, both animal and vegetable, are only natural growths from the lowest forms of life; that these lowest forms are a development, with new manifestations of energy, from inorganic matter; that compounds are derived from elements; and that the last are derivatives of some one element; but it must be borne in mind that this is only a theory.
342. New Theory of Chemistry. We have seen that heat lies at the basis of chemical as well as of physical changes. By the loss of heat, or perhaps by the change of potential into kinetic energy, in a nebulous parent mass, planets were formed, capable of supporting living organisms. Heat changes solids to liquids, and liquids to gases; it resolves compounds, or it aids chemical union. In every chemical combination heat is developed; in every case of dissociation heat is absorbed. Properly written, every equation should be: a + b = c + heat; e.g. 2 H + 0 = H2O + heat; or, c - a = b - heat; e.g. H2O - 2 H = 0 - heat. Another illustration is the combination of C and O, and the dissociation of CO2, as given on page 82. C + O2 = CO2 + energy. CO2 - O2 = C - energy. In fact, there are indications that the present theory of atoms and molecules of matter, as the foundation of chemistry, will at no distant day give place to a theory of chemistry based on the forms of energy, of which heat is a manifestation.
Chapter, LXII.
GAS VOLUMES AND WEIGHTS.
343. Oxygen.
Experiment 134.—Weigh accurately, using delicate balances, 5 g. KClO3, and mix with the crystals 1 or 2 g. of pure powdered MnO2. Put the mixture into a t.t. with a tight-fitting cork and delivery-tube, and invert over the water-pan, to collect the gas, a flask of at least one and a half liters' capacity, filled with water. Apply heat, and, without rejecting any of the gas, collect it as long as any will separate.
Then press the flask down into the water till the level in the flask is the same as that outside, and remove the flask, leaving in the bottom all the water that is not displaced. Weigh the flask with the water it contains; then completely fill it with water and weigh again.
Subtract the first weight from the second, and the result will evidently be the weight of water that occupies the same volume as the O collected. This weight, if expressed in grams, represents approximately the number of cubic centimeters of water,—since 1 cc. of water weighs lg,—or the number of cubic centimeters of O.
At the time the experiment is performed the temperature should be noted with a centigrade thermometer, and the atmospheric pressure with a barometer graduated to millimeters.
Suppose that we have obtained 1450 cc. of O, that the temperature is 27 degrees, and the pressure 758 mm.; we wish to find the volume and the weight of the gas at 0 degrees and 760 mm.
According to the law of Charles—the volume of a given quantity of gas at constant pressure varies directly as the absolute temperature. To reduce from the centigrade to the absolute scale, we have only to add 273 degrees. Adding the observed temperature, we have 273 degrees + 27 degrees = 300 degrees. Applying the above law to O obtained at 300 degrees A, we have the proportion below. Since the volume of O at 273 degrees will be less than it will at 300 degrees, the fourth term, or answer will be less than the third, and the second term must be less than the first. 300 : 273 :: 1450 : x. This would give the result dependent upon temperature alone.
By the law of Mariotte - Physics, - the volume of a given quantity of gas at a constant temperature varies inversely as the pressure. Applying this law to the O obtained at 758mm, we have the following proportion. The volume at 760mm will be less than at 758mm; or the fourth term will be less than the third; hence the second must be less than the first. 760: 758:: 1450: x. This would give the result dependent on pressure alone.
Combining the two proportions in one:—
300: 273 ):: 1450: x = 1316cc. 760: 758 )
1316cc=1.316 liters. It remains to find the weight of this gas. A liter of H weighs 0.0896g. The vapor density of O is 16. Hence 1.316 liters of O will weigh 1.316 X 16 X 0.0896 =1.89g.
(KClO3 = KCl + O3) From the equation (122.5 48) we make a proportion, ( 5 x)
122.5: 5:: 48: x = 1.95, and obtain, as the weight of O contained in 5g of KClO3, 1.95g. The weight we actually,obtained was 1.89g. This leaves an error of 0.06g, or a little over 4 per cent of error (0.06 / 1.95 = 0.03 +). The percentage of error, in performing this experiment, should fall within 10.
Some of the liabilities to error are as follows:—
1. Impure MnO2, which sometimes contains C. CO2 is soluble m H2O.
2. Solubility of O in water.
3. Escape of gas by leakage.
4. Moisture taken up by the gas.
5. Difference between the temperature of the gas and that of the air in the room.
6. Errors in weighing.
7. Want of accuracy in the weights and scales.
344. Hydrogen.
Experiment 135.—Weigh 5g, or less of sheet or granulated Zn, and put it into a small flask provided with a thistle-tube and a delivery-tube. Cover the Zn with water, and introduce through the thistle-tube measured quantities of HCl, a few cubic centimeters at a time. Collect the H over water in large flasks, observing the same directions as in removing O. Weigh the water, compute the volume of the gas, reduce it to the standard, and obtain the weight, as before. Should any Zn or other solid substance be left, pour off the water or filter it, weigh the dry residue, and deduct its weight from that of the Zn originally taken. Suppose the residue to weigh 0.5g. Make and solve the proportion from the equation:-
Zn + 2HCl = ZnCl2 + 2H. 65 2. 4.5 x.
Compute the percentage of errcr, as in the case of O. If the purity of the HCl be known, i.e. the weight of HCl gas in one cubic centimeter of the liquid, a proportion can be made between HCl and H, provided no free HCl is left in the flask. State any liabilities to error in this experiment.
PROBLEMS.
(1) A gas occupies 2000cc.when the barometer stands 750mm. What volume will it fill at 760mm?
(2) At 750mm my volume of O is 4 1/2 liters. What will it be at 730mm?
(3) At 825mm?
(4) At 200mm?
(5) Compute the volume of a gas at 70 degrees, which at 30 degrees is 150cc.
(6) At 0 degrees I have 3000cc.of O. What volume will it occupy at 100 degrees?
(7) I fill a flask holding 2 litres with H. The thermometer indicates 26 degrees, the barometer 762mm. What is the volume of the gas at 0 degrees and 760mm?
If the volumes of gases vary as above, it is evident that their vapor densities must vary inversely. A liter of H at 0 degrees weighs 0.0896. What will a liter of H weigh at 273 degrees? At 273 degrees the one liter has be- come two liters, one of which weighs 0.0448 (= 0.0896 / 2). The vapor density of a gas is inversely proportional to the temperature. Also, the vapor density is directly proportional to the pressure, since a liter of any gas under a pressure of one atmosphere is reduced to half a liter under two atmospheres.
PROBLEMS.
(1) Find the weight of a liter of O at 0 degrees; then compute the weight of a liter at 27 degrees.
(2) Find the weight of 500cc.of N2O at 60 degrees.
(3) Of 200 cc. of CO at -5 degrees.
(4) A given volume of O weighs 0.25g at a pressure of 750mm; find the weight of a like volume of O at 758mm.
APPENDIX.
INDIVIDUAL APPARATUS.
Each pupil should be provided with the apparatus given below, but in cases where great economy must be exercised different pupils may, by working at different times, use the same set. The author has selected apparatus specially adapted, as to exact dimensions, quality, and cheap- ness, for performing in the best way the experiments herein described, and sets or separate pieces of this, together with other apparatus and chemicals, can be had of the L.E. Knott Apparatus Co., 14 Ashburton Place, Boston, to which firm teachers are referred for catalogs.
4 wide-mouthed bottles (horse-radish size), with corks. 1 soda-bottle. 4 pieces window-glass (3 in. sq.). 2 pieces thick glass tubing (20 in. long, 4 in. outside diam.). 1 glass stirring-rod. 1 glass funnel (2 1/2 in. wide, 60 degrees). 2 pieces glass tubing (12 in. long; 5/8 in. diam.). 1 porcelain evaporating-dish (3 in. wide). 1 asbestus paper and 1 fine wire gauze (3 in. sq.). 1 iron (or tin) plate. 1 pair forceps. 1 triangular file and 1 round file. 1 copper wire (15 in. long). 6 test-tubes, and corks to fit. 1 wooden test-tube holder. 1 flask with cork (200cc). 1 Bunsen burner (or alcohol lamp). 1 iron ring-stand. 1 piece rubber tubing (18 in. long, 3/8 in. inside diam.). 4 reagent bottles (250cc), HCl, HNO3, H2SO4, NH4OH. 1 pneumatic trough.
Wherever in this work "Bunsen burner" or "lamp" is mentioned, if gas is not to be had, an alcohol lamp may be substituted.
GENERAL APPARATUS.
The following list includes apparatus needed for occasional use:—
Metric rules (20 or 30cm long). Scales with metric weights (1-200 g). Metric graduates (25 or 50cc). Filter papers. Metric graduates (500cc). Reagent bottles (250 and 500cc). Mouth blowpipes. Platinum wire and foil. Mortars and pestles. Test-tube racks. Thistle-tubes. Filter-stands. Beakers. Glass tubing (3/16 in., 1/4 in., and 1 in. outside). Rubber tubing (1/8 in., and 3/8 in. inside). Hessian crucibles. Porcelain crucibles. Electrolytic apparatus, including 2 or more Bunsen cells. Ignition-tubes. Steel glass-cutters. Wire-cutters. Calcium chloride tubes. Water baths. Thermometers. Barometers, etc.
APPENDIX.
CHEMICALS.
The following estimate is for twenty pupils: - Alcohol 1 pt Alum 1 oz Ammonium chloride 1/2 lb Ammonium hydrate 1 lb Ammonium nitrate. 1/2 lb Antimony (powdered metallic) 1/2 oz. Arsenic (powdered metallic) 1/2 oz. Arsenic trioxide..... 1 oz. Barium chloride..... 1 oz. Barium nitrate..... 1 oz. Beeswax....... 1 oz. Bleaching-powder.... 1/4 lb. Bone-black...... 1/2 lb. Bromine....... 1/4 lb. Calcium chloride.... 1 lb. Calcium fluoride (powdered) 1 lb. Cannel coal 1 lb Carbon disulphide 1/4 lb Chlorhydric acid 6 lb Cochineal 1 oz Copper (filings) 2 lb. Copper nitrate 1 oz Copper oxide 1/4 lb. Ether (sulphuric) 1/4 lb Ferrous sulphide 1 lb. Ferrous sulphate 1/4 lb Indigo 1/4 lb Iodine 1 oz Iron (filings or turnings) 1 lb. Lead (sheet) 4 lb Lead acetate 1 oz Lead nitrate 1/4 lb Litmus 1/2 oz Litmus paper 3 sheets Magnesium ribbon.... 3 ft. Manganese dioxide.... 2 lb. Mercurous nitrate.... 1/2 oz. Nitric acid 3 lb. Oxalic acid 1/4 lb Phosphorus 1/4 lb Potassium (metallic) 1/8 oz Potassium bromide 1/4 lb. Potassium dichromate 1/4 lb. Potassium chlorate 2 lb. Potassium hydrate 1/4 lb. Potassium iodide 2 oz Potassium nitrate 1/4 llb Silver nitrate 1 oz. Sodium 1/8 oz. Sodium carbonate 1/4 lb Sodium hydrate 1 lb. Sodium nitrate 1/2 lb Sodium silicate..... 1/2lb Turkey red cloth.... 1/2yd Sodium sulphate..... 1/4lb Turpentine(spirits). 1/4lb Sodium sulphide..... 1/4lb Zinc(granulated).... 2lb Sodium thiosulphate. 1/4lb Zinc foil........... 3ft Sulphur............. 2lb Sulphuric acid...... 12lb
Additional Material
These substances are best obtained of local dealers.
Calcium carbonate(marble)..... 1lb Molasses...................... 1pt Calcium oxide(unslaked lime).. 1lb Sodium chloride(fine)......... 1lb Charcoal...................... 1lb Sodium chloride(coarse)....... 1lb Sheet lead.................... 4lb Sugar......................... 1/2lb
FOR EXAMINATION
Those in capitals are most important
Rocks and Minerals. ARGILLITE, ARESENIC, ARSENOPYRITE, Barite, CALCITE, CASSITERITE, CHALCOPYRITE, CHALK, CINNABAR, COPPER (native), Corundum, Dolomite, EMERY, FELDSPAR, Flint, GALENITE, GRANITE, GRAPHITE, GYPSUM, HEMATITE, Hornblende, Jasper, LIMONITE, MAGNESITE, MAGNETITE, MALACHITE, Meerschaum, MICA, OBSIDIAN, Orpiment, PYRITE, QUARTZ, Realgar, SAND, SERPENTINE, SIDERITE, SPHALERITE, Talc, ZINCITE
Metals and Alloys.
Aluminium, Iron (cast), Aluminium bronze. Pewter, Bell metal, Solder, Brass, Steel, Bronze, Type metal, Copper, Tin foil, Galvanized iron, Tin (bright plate and terne plate), German silver, Zinc (sheet). Iron (wrought)
Additional Compounds, for Examination:
Copper acetate, Lead carbonate, Copper arsenite, Red lead, Copper nitrate, Magnesia alba, Copper sulphate, Smalt, Lead dioxide, Vermilion. Lead protoxide,
TABLE OF SOLUTIONS.
Number of grams of solids to be dissolved in 500cc of water.
AgNO3......... 25 K2Al2(SO4)4...... 50 BaCl2......... 50 KBr.... 25 Ba(N0 3)2........ 30 K2Cr207........ 50 CaClz......... 60 KI.......... 25 Ca(OH)2...... saturated KOH....... 60 CaS04....... saturated NaICOS........ 50 CUC12 50 NaOH 60 Cu(N03)......... 50 NalSl03....... saturated FeS04......... 50 NH,N03........ 50 HgC12......... 30 Pb(C2H302)2...... 50 HgN03..... 25 + 25 HN03 Pb(NOs)2....... . 50
Other solutions....saturated.
Indigo solution (sulphindigotic acid) is prepared by heating for several hours over a water bath, a mixture of ten parts of H 2SO4 with one of indigo, and, after letting it stand twenty-four hours, adding twenty parts of water and filtering.
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I.P. Bishop, State Normal School, Buffalo, N.Y.:
"The book seems to have all the essentials of a first-class text for high school work; viz., conciseness, clearness, and the results of recent research."
YOUNG'S GENERAL ASTRONOMY
A Text-book for Colleges and Technical Schools. By CHARLES A . YOUNG, Professor of Astronomy in the College of New Jersey. 8vo. viii + 551 pages. Half morocco. Illustrated with over 250 cuts and and diagrams, and supplemented with the necessary tables. Mailing price, $2.50; for introduction, $2.25.
In amount, the work has been adjusted as closely as possible to the prevailing courses of study in our colleges. By omitting the fine print, a briefer course may be arranged.
The eminence of Professor Young as an original investigator in astronomy, a lecturer and writer on the subject, and an instructor of college classes, and his scrupulous care in preparing this volume, led the publishers to present the work with the highest confidence; and this confidence has been fully justified by the event. More than one hundred colleges adopted the work within a year from its publication, and it is conceded to be the best astronomical text-book of its grade to be found anywhere.
Edw. C. Pickering, Prof. of Astronomy, Harvard University:
"I think this work the best of its kind, and admirably adapted to its purpose."
S.P. Langley, Sec. Smithsonian Inst., Washington, D.C.:
"I know no better book (not to say as good a one) for its purpose, on the subject."
AN INTRODUCTION TO SPHERICAL AND PRACTICAL ASTRONOMY
By DASCOM GREENE, Professor of Mathematics and Astronomy in the Rensselaer Polytechnic Institute, Troy, N.Y. NW. Cloth. Illustrated. viii + 158 pages. Mailing price, $1.60; for introduction, $1.50.
The book is intended for class-room use and affords such a preparation as the student needs before entering upon the study of the larger and more elaborate works on this subject.
The appendix contains an elementary exposition of the method of least squares.
Daniel Carhart, Act. Prof. Mathematics, Western Univ. of Pa., Allegheny, Pa.:
"Professor Greene has supplied that which is needed to make the usual course in Astronomy in our colleges more practical."
Rodney G. Kimball, Polytechnic Institute, Brooklyn, N.Y.:
"The hasty examination which I have given it has left a very favorable impression as to its merits as a judicious compound of the practical work which it professes to cover."
SCHEINER'S ASTRONOMICAL SPECTROSCOPY
Department of Special Publication.—Revised Edition. Translated, revised and enlarged by E.B. FROST, Professor of Astronomy in Dartmouth College. 8vo. Half leather. Illustrated. xiii + 482 pages. Price by mail, $5.00; for introdoctiort, $4.75.
This work aims to explain the most practical and modern methods of research, and to state our present knowledge of the constitution, physical condition alld motions of the heavenly bodies, as revealed by the spectroscope.
Edward S. Holden, Director of the Lick Observatory, Mt. Hamilton, California:
"I congratulate you on the appearance of this very important book; it is indispensable to all astronomers and students of spectroscopy."
ELEMENTS OF PLANT ANATOMY
By EMILY L. GREGORY, Professor of Botany in Barnard College. 8vo. Cloth. viii + 148 pages. Illustrated. Mailing price, $1.35; for introduction, $1.25.
This book is designed as a text-book for students who have already some knowledge of general botany. It consists of an outline of the principal facts of plant anatomy, in a form available not only for those who wish to specialize in botany but for all who wish to know the leading facts about the inner structure of plants. It affords a preparation for the study of the more intricate and difficult questions of plant anatomy and physiology, while it is especially adapted to the wants of students, who need a practical knowledge of plant structure.
ELEMENTS OF STRUCTURAL AND SYSTEMATIC BOTANY
For High Schools and Elementary College Courses. By DOUGLAS H. CAMPBELL, Professor of Botany in the Leland Stanford Junior University. 12mo. Cloth. ix + 253 pages. Price by mail, $1.25; for introduction, $1.12.
The special merit of this book is that it begins with the simple forms, and follows the order of nature to the complex ones.
PLANT ORGANIZATION
By R. HALSTEAD WARD, formerly Professor of Botany in the Rensselaer Polytechnic Institute, Troy, N.Y. Quarto. 176 pages. Illustrated. Flexible boards. Mailing price, 85 cents; for introduction, 75 cents.
ELEMENTARY METEOROLOGY
By WILLIAM MORRIS DAVIS, Professor of Physical Geography in Harvard College. With maps and charts. 8vo. Cloth. xi + 355 pages. Mailing price, $2.70; for introduction, $2.50.
This work is believed to be very opportune, since no elementary work on the subject has been issued for over a quarter of a century. It represents the modern aspects of the science. It is adapted to the use of advanced students, and will meet the needs of members of the National and State Weather Services who wish to acquaint themselves with something more than methods of observation.
The essential theories of modern Meteorology are presented in such form that the student shall perceive their logical connection, and shall derive from their mastery something of the intellectual training that comes with the grasp of well-tested conclusions.
The charts of temperature, pressure, winds, etc., are reduced from the latest available sources, while the diagrams freely introduced through the text are for the most part new.
A.W. Greeley, retired Brigadier General U.S.A., and formerly Chief of Signal Office, Washington:
"A valuable and timely contribution to scientific text-books."
Winslow Upton, Professor of Astronomy, Brown University:
"The best general book on the subject in our language."
Wm. B. Clark, Professor of Geology, Johns Hopkins University:
"An excellent book and of great value to the teacher of meteorology."
David Todd, Professor of Astronomy, Amherst College:
"Clear, concise, and direct. To teach meteorology with it must be a delight."
MOLECULES AND THE MOLECULAR THEORY OF MATTER
Department of Special Publioation. By A. D. RISTEEN. 8vo. Cloth. Illustrated. viii + 223 pages. Retail price, $2.00
This work is a complete popular exposition of the molecular theory of matter, as it is held by the leading physicists of today. Considerable space is devoted to the kinetic theory of gases. Liquids also are discussed, and solids receive much attention. There is also a division discussing the methods that have been proposed for finding the sizes of molecules, and here, as elsewhere throughout the book, the methods described are illustrated by numerical examples. The last division of the book touches upon the constitution of molecules. The subject is everywhere treated from a physical standpoint.
END OF AN INTRODUCTION TO CHEMICAL SCIENCE
INFORMATION ABOUT THIS ELECTRONIC EDITION
The original edition of this text was published by Ginn and Company, Publishers, Boston, U.S.A. in 1896. The typography was by J.S. Cushing and Co., Boston and the Presswork was by Ginn and Co., Boston. The book was "Entered according to Act of Congress, in the year 1887, by R.P. Williams, in the Office of the Librarian of Congress, at Washington."
This electronic text was prepared by John Mamoun with help from numerous other proofreaders, including those associated with Charles Franks' Distributed Proofreaders website. Thanks to R. Zimmerman, D. Starner, B. Schak, K. Rieff, D. Kokales, N. Harris, K. Peterson, E. Beach, W.M. Maull, M. Beauchamp J. Roberts and others for proofing this e-text.
This e-text is public domain, freely copyable and distributable for any non-commercial purpose, and may be included without royalty or permission on a mass media storage product, such as a cd-rom, that contains at least 50 public domain electronic texts, whether offered for non-commercial or commercial purposes. Any other commercial usage requires permission.
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