Detection.—Boron in small quantities will escape detection unless specially looked for, but there is no difficulty in detecting its presence. Heated in the Bunsen-burner flame with "Turner's test," it gives an evanescent yellowish-green colour, due to fluoride of boron (BF_{3}). "Turner's test" is a mixture of 5 parts of bisulphate of potash and 1 part of fluor spar. Boric acid itself imparts a characteristic green colour to the flame, which gives a spectrum made up of four well-marked and equidistant lines, three in the green and one in the blue. Solutions of boric acid give with "turmeric paper," which has been dipped into it and dried, a characteristic red tint. This is a very delicate test, but in trying it a blank experiment should be carried out alongside with a solution made up of the same re-agents which have been used in liberating the boric acid in the sample.

Solution and Separation.—The solution presents no difficulty, but the separation is troublesome. The best method is that of Gooch; who, if necessary, first fuses with carbonate of soda, and after the removal of chlorides and fluorides (by nitrate of silver or a lime salt), evaporates the aqueous extract with nitric or acetic acid to dryness in a retort and, subsequently, with repeated doses of 10 c.c. each of methyl alcohol. The distillate contains the boron as boric acid. Half a gram of the trioxide (B{2}O{3}) is completely carried over by two evaporations, each with 10 c.c. of the alcohol; but if water or foreign salts are present, more than this is required. In ordinary cases six such evaporations are sufficient for 0.2 gram of the oxide.[123]

GRAVIMETRIC DETERMINATION.

Before the introduction of Gooch's process it was usual to determine the boron trioxide "by difference." If the alcoholic distillate containing the boric acid is digested with about 1 gram (a known weight) of lime for ten or fifteen minutes, the alcohol can be evaporated off without danger of loss. Either calcium nitrate or acetate (which will be formed at the same time) yields lime upon subsequent ignition. Consequently, the increase in weight, after ignition, upon that of the lime taken gives the amount of boron trioxide present. The trioxide contains 31.4 per cent. of boron (B). Since magnesia does not form a soluble hydrate it cannot satisfactorily be used instead of lime.



The apparatus required is shown in fig. 82. It consists of a small retort or evaporating vessel made out of a pipette of 200 c.c. capacity. This is heated by means of a paraffin-bath at 130 or 140 C. It is connected with an upright condenser, at the lower end of which is a small flask which serves as a receiver.

The quantity of the borate taken should contain not more than 0.2 gram of the trioxide. Insoluble compounds are "dissolved in nitric acid at once, or, if necessary, first fused with sodium carbonate." With soluble and alkaline borates sufficient nitric acid is added to render it faintly acid. The solution is then introduced into the retort.

"The lime, to retain the boric acid in the distillate, is ignited in the crucible in which the evaporation of the distillate is to be made subsequently." It is then cooled in the desiccator for ten minutes, and weighed. The lime is transferred to the receiving flask and slaked with a little water. The retort is lowered into the bath so that "only the rear dips below the surface." The evaporation is carried to dryness, the retort being lowered further into the bath as the evaporation proceeds. Ten c.c. of methyl alcohol are introduced upon the residue, and the evaporation again started. Six such portions of alcohol are thus distilled and 2 c.c. of water are introduced and evaporated between the second and third, as also between the fourth and fifth distillations. If acetic acid is used instead of nitric in the first instance this addition of water is unnecessary.

The distillate is evaporated in the crucible ignited over the blowpipe, cooled in the desiccator for ten minutes and weighed. The increase in weight gives the boron trioxide. The results tend to be from 1 to 2 milligrams too high.

VOLUMETRIC METHOD.

This method is applicable to the indirect determination of boric acid in borax and similar compounds. It is based on the measurement of the quantity of normal solution of acid required to replace the boric acid, and, consequently, is rather a measure of the soda present. The process is an alkalimetric one, and is carried out as follows:—Weigh up 3 grams of the sample and dissolve in water. Tint with methyl orange, and run in from an ordinary burette normal solution of sulphuric acid until a pink tint is got. 100 c.c. of the normal solution of acid are equal to 7.0 grams of boron trioxide (B_{2}O_{3}), or 10.1 grams of anhydrous borax (Na_{2}B_{4}O_{7}).

Examination of Borax.—In addition to the determination just given, the following determinations are also required:—

Water.—Take about 2 grams and heat to tranquil fusion in a platinum crucible. Count the loss in weight as water.

Sulphuric Oxide.—Take 2 grams, dissolve in water, acidify with hydrochloric acid, filter, and precipitate with barium chloride. Wash the precipitate, ignite, and weigh as barium sulphate (see Sulphur).

Chlorine.—Take 2 grams, dissolve in water, acidify with nitric acid, filter, and add silver nitrate. Collect, wash, and weigh the precipitate as silver chloride.

Alumina.—Take 5 or 10 grams, dissolve in water, boil, add ammonia in slight excess, and filter off the precipitate when it has settled. Wash with hot water, ignite, and weigh as alumina (Al{2}O{3}).

FOOTNOTES:

[113] If the dishes show a manganese stain, wash them out with a few drops of hydrochloric and sulphurous acids. Pass the acid liquor through the same small filter but collect the liquor apart. Make ammoniacal and again pass through the filter, this time collecting the liquid with the main filtrate.

[114] This rarely amounts to more than 1 milligram.

[115] To make this, dissolve 1 gram of titanium oxide by fusing for some time with an excess of bisulphate of potash and dissolve out with cold water and sulphuric acid. Dilute to 1 litre, having previously added not less than 50 c.c. of strong sulphuric acid: 1 c.c. will contain .01 gram of TiO{2}. For the assay take 10 c.c. of this, add 2 c.c. of peroxide of hydrogen and dilute to 100 c.c. Run this from a burette into the flask until the colour equals that of the assay. Each c.c. equals 1 milligram of TiO{2}. Fluorides must be absent.

[116] C + O{2} = CO{2}

[117] For example, soluble organic acids formed by partial oxidation with nitric acid.

[118] For coals, and other bodies containing sulphur, chromate of lead should be used instead of oxide of copper; and the temperature should be limited to dull redness.

[119] This may be prepared by dissolving 534 grams of ammonium chloride and 854 grams of crystallized cupric chloride (CuCl{2}.2H{2}O) in hot water and crystallizing.

[120] Soda-lime is made by dissolving 100 grams of "soda" in water, and carefully slaking 200 grams of lime with it. Evaporate to dryness in an iron dish and ignite at a low red heat in a crucible. Use the small lumps.

[121] Made by diluting 1 part by measure of saturated lime-water up to 10 with recently boiled distilled water.

[122] See under Gasometric Assays.

[123] See "A Method for the Separation and Estimation of Boric Acid," by F.A. Gooch, Chemical News, January 7, 1887.



APPENDIX A.

TABLE OF ATOMIC WEIGHTS AND OTHER CONSTANTS.

- - Symbols. Names. Atomic Specific Melting Weights. Gravity. Points. - - C. Ag Silver 107.9 10.5 1000 Al Aluminium 27.0 2.7 700 As Arsenic 75.0 5.9 Au Gold 197.3 19.2 1200 B Boron 11.0 2.7 Ba Barium 137.0 4.0 Be Beryllium 9.0 2.1 Bi Bismuth 208.9 9.8 270 Br Bromine 80.0 3.2 -25 C Carbon 12.0 Ca Calcium 40.0 1.6 Cd Cadmium 112.0 8.6 315 Ce Cerium 140.2 6.7 Cl Chlorine 35.5 Co Cobalt 59.0 8.5 Cr Chromium 52.1 7.3 Cs Caesium 132.9 1.9 25 Cu Copper 63.4 8.9 1090 Di Didymium 142.3 6.5 Er Erbium 166.3 F Fluorine 19.0 Fe Iron 56.0 7.8 Ga Gallium 69.0 5.9 30 Ge Germanium 72.3 H Hydrogen 1.0 Hg Mercury 200.0 13.6 -40 I Iodine 126.8 4.9 106 In Indium 113.7 7.4 175 Ir Iridium 193.1 22.4 K Potassium 39.1 0.86 62.5 La Lanthanum 138.2 6.1 Li Lithium 7.0 0.59 180 Mg Magnesium 24.3 1.7 Mn Manganese 55.0 8.0 Mo Molybdenum 96.0 8.6 N Nitrogen 14.0 Na Sodium 23.0 0.97 95.6 Nb Niobium 94.0 4.1 Ni Nickel 58.7 8.9 O Oxygen 16.0 Os Osmium 191.7 22.4 P Phosphorus 31.0 1.8 44 Pb Lead 206.9 11.4 334 Pd Palladium 106.6 11.4 1350 Pt Platinum 195.0 21.5 2000 Rb Rubidium 85.5 1.5 38.5 Rh Rhodium 103.5 12.1 Ru Ruthenium 101.6 11.4 S Sulphur 32.0 2.0 115 Sb Antimony 120.0 6.7 425 Se Selenium 79.0 4.8 100 Si Silicon 28.4 2.0 Sn Tin 119.0 7.3 235 Sr Strontium 87.6 2.5 Ta Tantalum 182.6 Te Tellurium 125.0 6.2 480 Th Thorium 232.6 7.8 Ti Titanium 48.0 5.3 Tl Thallium 204.2 11.9 294 U Uranium 239.6 18.4 V Vanadium 51.4 5.5 W Tungsten 184.0 19.1 Y Yttrium 89.1 Yb Ytterbium 173.0 Zn Zinc 65.3 6.9 423 Zr Zirconium 90.6 4.1

The atomic weights in this table are in accord with the numbers given by F.W. Clarke (Dec. 6, 1890), chief chemist of the United States Geological Survey.



Nitric Acid.

_Table showing the percentage, by Weight, of Real Acid_ (HNO_{3}) _in Aqueous Solutions of Nitric Acid of different Specific Gravities. Temperature_, 15 C.

- - - - - - 1.530 100.0 1.405 66.0 1.205 33.0 1.527 99.0 1.400 65.0 1.198 32.0 1.524 98.0 1.395 64.0 1.192 31.0 1.520 97.0 1.390 63.0 1.185 30.0 1.516 96.0 1.386 62.0 1.179 29.0 1.513 95.0 1.380 61.0 1.172 28.0 1.509 94.0 1.374 60.0 1.166 27.0 1.506 93.0 1.368 59.0 1.159 26.0 1.503 92.0 1.363 58.0 1.152 25.0 1.499 91.0 1.358 57.0 1.145 24.0 1.495 90.0 1.353 56.0 1.138 23.0 1.492 89.0 1.346 55.0 1.132 22.0 1.488 88.0 1.341 54.0 1.126 21.0 1.485 87.0 1.335 53.0 1.120 20.0 1.482 86.0 1.329 52.0 1.114 19.0 1.478 85.0 1.323 51.0 1.108 18.0 1.474 84.0 1.317 50.0 1.102 17.0 1.470 83.0 1.311 49.0 1.096 16.0 1.467 82.0 1.304 48.0 1.089 15.0 1.463 81.0 1.298 47.0 1.083 14.0 1.460 80.0 1.291 46.0 1.077 13.0 1.456 79.0 1.284 45.0 1.071 12.0 1.452 78.0 1.277 44.0 1.065 11.0 1.449 77.0 1.270 43.0 1.060 10.0 1.445 76.0 1.264 42.0 1.053 9.0 1.442 75.0 1.257 41.0 1.047 8.0 1.438 74.0 1.251 40.0 1.041 7.0 1.435 73.0 1.244 39.0 1.034 6.0 1.431 72.0 1.238 38.0 1.028 5.0 1.427 71.0 1.232 37.0 1.022 4.0 1.423 70.0 1.225 36.0 1.016 3.0 1.418 69.0 1.218 35.0 1.010 2.0 1.414 68.0 1.212 34.0 1.004 1.0 1.410 67.0 - - - - -

HYDROCHLORIC ACID.

Table showing the percentage, by Weight, of Real Acid (HCl) in Aqueous Solutions of Hydrochloric Acid of different Specific Gravities. Temperature, 15 C.

- - - - 1.2000 40.78 1.1410 28.54 1.0798 16.31 1.1982 40.37 1.1389 28.13 1.0778 15.90 1.1964 39.96 1.1369 27.72 1.0758 15.49 1.1946 39.55 1.1349 27.32 1.0738 15.08 1.1928 39.14 1.1328 26.91 1.0718 14.68 1.1910 38.74 1.1308 26.50 1.0697 14.27 1.1893 38.33 1.1287 26.10 1.0677 13.86 1.1875 37.92 1.1267 25.69 1.0657 13.45 1.1857 37.51 1.1247 25.28 1.0637 13.05 1.1846 37.11 1.1226 24.87 1.0617 12.64 1.1822 36.70 1.1206 24.46 1.0597 12.23 1.1802 36.29 1.1185 24.06 1.0577 11.82 1.1782 35.88 1.1164 23.65 1.0557 11.41 1.1762 35.47 1.1143 23.24 1.0537 11.01 1.1741 35.07 1.1123 22.83 1.0517 10.60 1.1721 34.66 1.1102 22.43 1.0497 10.19 1.1701 34.25 1.1082 22.02 1.0477 9.78 1.1681 33.84 1.1061 21.61 1.0457 9.38 1.1661 33.43 1.1041 21.20 1.0437 8.97 1.1641 33.03 1.1020 20.79 1.0417 8.56 1.1620 32.62 1.1000 20.39 1.0397 8.15 1.1599 32.21 1.0980 19.98 1.0377 7.75 1.1578 31.80 1.0960 19.57 1.0357 7.34 1.1557 31.40 1.0939 19.16 1.0337 6.93 1.1536 30.99 1.0919 18.76 1.0318 6.52 1.1515 30.58 1.0899 18.35 1.0298 6.11 1.1494 30.17 1.0879 17.94 1.0279 5.51 1.1473 29.76 1.0859 17.53 1.0259 5.30 1.1452 29.36 1.0838 17.12 1.0239 4.89 1.1431 28.95 1.0818 16.72 1.0200 4.01 - - - -

AMMONIA.

_Table showing the percentage, by Weight, of Real Ammonia_ (NH_{3}) _in Aqueous Solutions of Ammonia of different Specific Gravities. Temperature_, 14 C.

0.8844 36.0 0.9145 23.6 0.9534 11.6 0.8852 35.6 0.9156 23.2 0.9549 11.2 0.8860 35.2 0.9168 22.8 0.9563 10.8 0.8868 34.8 0.9180 22.4 0.9578 10.4 0.8877 34.4 0.9191 22.0 0.9593 10.0 0.8885 34.0 0.9203 21.6 0.9608 9.6 0.8894 33.6 0.9215 21.2 0.9623 9.2 0.8903 33.2 0.9227 20.8 0.9639 8.8 0.8911 32.8 0.9239 20.4 0.9654 8.4 0.8920 32.4 0.9251 20.0 0.9670 8.0 0.8929 32.0 0.9264 19.6 0.9685 7.6 0.8938 31.6 0.9277 19.2 0.9701 7.2 0.8948 31.2 0.9289 18.8 0.9717 6.8 0.8957 30.8 0.9302 18.4 0.9733 6.4 0.8967 30.4 0.9314 18.0 0.9749 6.0 0.8976 30.0 0.9327 17.6 0.9765 5.6 0.8986 29.6 0.9340 17.2 0.9781 5.2 0.8996 29.2 0.9353 16.8 0.9790 4.8 0.9006 28.8 0.9366 16.4 0.9807 4.6 0.9016 28.4 0.9380 16.0 0.9823 4.2 0.9026 28.0 0.9393 15.6 0.9839 3.8 0.9036 27.6 0.9407 15.2 0.9855 3.4 0.9047 27.2 0.9420 14.8 0.9873 3.0 0.9057 26.8 0.9434 14.4 0.9890 2.6 0.9068 26.4 0.9449 14.0 0.9907 2.2 0.9078 26.0 0.9463 13.6 0.9924 1.8 0.9089 25.6 0.9477 13.2 0.9941 1.4 0.9100 25.2 0.9491 12.8 0.9959 1.0 0.9111 24.8 0.9505 12.4 0.9975 0.6 0.9122 24.4 0.9520 12.0 0.9991 0.2 0.9133 24.0

SULPHURIC ACID.

Table showing the percentage, by Weight, of Real Acid (H{2}SO{4}) in Aqueous Solutions of Sulphuric Acid of varying Specific Gravity. Temperature, 15 C.

1.838 100.0 1.568 66.0 1.247 33.0 1.840 99.0 1.557 65.0 1.239 32.0 1.841 98.0 1.545 64.0 1.231 31.0 1.841 97.0 1.534 63.0 1.223 30.0 1.840 96.0 1.523 62.0 1.215 29.0 1.838 95.0 1.512 61.0 1.206 28.0 1.836 94.0 1.501 60.0 1.198 27.0 1.834 93.0 1.490 59.0 1.190 26.0 1.831 92.0 1.480 58.0 1.182 25.0 1.827 91.0 1.469 57.0 1.174 24.0 1.822 90.0 1.458 56.0 1.167 23.0 1.816 89.0 1.448 55.0 1.159 22.0 1.809 88.0 1.438 54.0 1.151 21.0 1.802 87.0 1.428 53.0 1.144 20.0 1.794 86.0 1.418 52.0 1.136 19.0 1.786 85.0 1.408 51.0 1.129 18.0 1.777 84.0 1.398 50.0 1.121 17.0 1.767 83.0 1.388 49.0 1.113 16.0 1.756 82.0 1.379 48.0 1.106 15.0 1.745 81.0 1.370 47.0 1.098 14.0 1.734 80.0 1.361 46.0 1.091 13.0 1.722 79.0 1.351 45.0 1.083 12.0 1.710 78.0 1.342 44.0 1.075 11.0 1.698 77.0 1.333 43.0 1.068 10.0 1.686 76.0 1.324 42.0 1.061 9.0 1.675 75.0 1.315 41.0 1.053 8.0 1.663 74.0 1.306 40.0 1.046 7.0 1.651 73.0 1.297 39.0 1.039 6.0 1.639 72.0 1.289 38.0 1.032 5.0 1.627 71.0 1.281 37.0 1.025 4.0 1.615 70.0 1.272 36.0 1.019 3.0 1.604 69.0 1.264 35.0 1.013 2.0 1.592 68.0 1.256 34.0 1.006 1.0 1.580 67.0



APPENDIX B.

ESTIMATION OF SMALL QUANTITIES OF GOLD.[124]

In the case of small buttons of gold the weight can be determined more easily and accurately by measuring with the help of a microscope than by the actual use of a balance. Moreover, the method of measurement is applicable to the determination of quantities of gold too minute to affect even the most delicate balance.

For quantities of gold of from .5 to .005 milligram a microscope with 1/2 inch objective and B eyepiece is suitable. The measurements are made with the help of a scale engraved (or, better, photographed) on a circular piece of glass which rests on the diaphragm of the eyepiece. This scale and the object upon the stage can be easily brought into focus at the same time. The button of gold obtained by cupelling is loosened from the cupel by gently touching with the moistened point of a knife; it generally adheres to the knife, and is then transferred to a glass slide. The slide is placed on the stage of the microscope, illuminated from below; and the button is brought into focus, and so placed that it apparently coincides with the scale. The diameters in two or three directions (avoiding the flattened surface) are then read off: the different directions being got by rotating the eyepiece. The mean diameter is taken. The weight of the button is arrived at by comparing with the mean diameter of a standard prill of gold of known weight. The weights are in the proportion of the cubes of the diameters. For example, suppose a prill has been obtained which measures 12.5 divisions of the scale, and that a standard prill weighing 0.1 milligram measures 11.1 divisions. The weight will be calculated as follows:

11.1^{3} : 12.5^{3} :: 0.1 : x

0.112.512.512.5 x = —————————— = 0.143 milligram. 11.111.111.1

The calculations are simplified by the use of a table of cubes. The standard prills used in the comparison should not differ much in size from the prills to be determined. They are prepared by alloying known weights of gold and lead, so as to get an alloy of known composition, say one per cent. gold. Portions of the alloy containing the weight of gold required (say 0.1 milligram) are then weighed off and cupelled on small smooth cupels, made with the finest bone-ash. Care must be taken to remove the cupels as soon as cupellation has finished. Several standard prills of the same size should be made at the same time, and their mean diameter calculated. The lead for making the gold-lead alloy is prepared from litharge purified by reducing from it about 10 per cent. of its lead by fusion with a suitable proportion of flour; the purified litharge is powdered, mixed with sufficient flour and reduced to metal.

In determining the gold contained in small buttons of silver-gold alloy obtained in assaying (and in which the silver is almost sure to be in excess of that required for parting), transfer the button from the cupel to a small clean porcelain crucible; pour on it a drop or two of nitric acid (diluted with half its bulk of water), and heat gently and cautiously until action has ceased. If the residual gold is broken up, move the crucible so as to bring the particles together, so that they may cohere. Wash three or four times with distilled water, about half filling the crucible each time and decanting off against the finger. Dry the crucible in a warm place; and when dry, but whilst still black, take the gold up on a small piece of pure lead. Half a grain of lead is sufficient, and it is best to hold it on the point of a blunt penknife, and press it on the gold in the crucible. The latter generally adheres. Transfer to a small smooth cupel and place in the muffle. When the cupellation has finished, the button of gold is measured as already described.

PRACTICAL NOTES ON THE IODIDE PROCESS OF COPPER ASSAYING.

For the following remarks and experiments we are indebted to Mr. J.W. Westmoreland, who has had considerable experience with the process. Having dissolved the ore he converts the metals into sulphates by evaporating with sulphuric acid. The copper is then separated as subsulphide by means of hyposulphite of soda, and the precipitate is washed, dried, and calcined. The resulting oxide of copper is then dissolved in nitric acid; and to the concentrated solution, a saturated solution of carbonate of soda is added in sufficient quantity to throw down a considerable proportion of the copper. Acetic acid is added to dissolve the precipitate, and when this is effected more of the acid is poured on so as to render the solution strongly acid. To this potassium iodide crystals are added in the proportion of ten parts of iodide to each one part of copper supposed to be present. The solution is then titrated with "hypo" as usual.

For the examination of technical products experiments made in sulphuric acid solutions have no value, since arsenic acid, which is generally present to a greater or less extent, affects the end reaction. In such solutions bismuth may also interfere.

The solution best suited for the assay is one containing acetate of soda and free acetic acid. The presence of acetate of soda counteracts the interference of arsenic and of bismuth.

The return of the blue colour after titration is due to the excessive dilution of the assay, or to an insufficiency of potassium iodide, or to the presence of nitrous fumes. The interference of an excess of sodium acetate is avoided by adding more iodide crystals to the extent of doubling the usual amount.

The interference of lead can be avoided by the addition of sulphuric acid or of phosphate of soda to the acid solution containing the copper, and before neutralising with carbonate of soda. The end reaction is, however, with care distinguishable without this addition. The following experiments, each containing .0648 gram of lead, were made by him in illustration:

-+ -+ -+ - Copper taken. Reagent added. Copper found. End reaction. -+ -+ -+ - .2092 gram .2077 gram fairly satisfactory .2101 " .2092 " " .2167 " sulphuric acid .2152 " " .2117 " " .2108 " " .2109 " phosphate of soda .2092 " good, colourless .2205 " " .2174 " rather yellow -+ -+ -+ -

Effect of Sodium Acetate.—Each solution contained .3343 gram of copper.

a.b.c. d. e. f. g. grams. grams. grams. grams. grams. "Acetate" added — 16.2 16.2 16.2 16.2 "Iodide" added 3.5 3.5 7.0 3.5 7.0 Copper found .3343 .3324 .3351 .3269 .3356

In these experiments, except with the excessive quantities of acetate of soda and the insufficiency of potassium iodide in the cases of c and f, there was no difficulty with the after-blueing.

METHOD OF SEPARATING COBALT AND NICKEL.

The following method of separating and estimating cobalt and nickel has been described by Mr. James Hope,[125] with whom it has been in daily use for several years with completely satisfactory results.

The quantity of ore taken should contain about .5 gram of the mixed metals. It is dissolved in hydrochloric acid or aqua regia, and the solution evaporated to dryness. The residue is taken up with dilute hydrochloric acid and hot water. The solution is filtered off from the silica, freed from second group metals by treatment with sulphuretted hydrogen and filtered, and after oxidation with nitric acid is separated from iron and alumina by the basic acetate method (page 233). The precipitate is redissolved in a little hydrochloric acid, and again precipitated by sodium acetate. The two filtrates are mixed and treated with a little acetic acid, and the cobalt and nickel are then precipitated as sulphides by a current of sulphuretted hydrogen. The precipitate is filtered off, washed, dried, and calcined, and the resulting oxides are weighed to get an idea as to the quantity of the two metals present.

The calcined precipitate is dissolved in a small covered beaker in aqua regia with the help of a few drops of bromine to remove any separated sulphur, and the solution evaporated to dryness with a few drops of sulphuric acid. The residue is dissolved in hot water, diluted to about 50 c.c., and heated to boiling. About 2 grams (four times the quantity of mixed metals present) of ammonium phosphate (AmH_{2}PO_{4}) are weighed off, dissolved in the smallest possible quantity of water, and boiled for a minute or two with a few c.c. of dilute sulphuric acid. This is added to the boiling-hot solution of cobalt and nickel, which is then treated cautiously with dilute ammonia until the precipitate partially dissolves. The addition of the ammonia is continued drop by drop with constant stirring, until the cobalt comes down as a pink precipitate of ammonium cobalt phosphate (AmCoPO_{4}). The beaker is placed on the top of a water bath with occasional stirring for five or ten minutes. The blue liquid containing the nickel is decanted through a small filter and the precipitate is dissolved with a few drops of dilute sulphuric acid. The resulting solution is treated with a small excess of ammonium phosphate and the cobalt again precipitated by the cautious addition of ammonia exactly as before. The precipitate containing the whole of the cobalt is filtered off and washed with small quantities of hot water. The filtrate is added to the previous one containing the greater part of the nickel.

The ammonium cobalt phosphate is dried, transferred to a platinum crucible, and ignited over a Bunsen flame for fifteen or twenty minutes. A purple coloured cobalt pyrophosphate (Co_{2}P_{2}O_{7}) is thus formed, and is weighed. It contains 40.3 per cent. of cobalt.

The mixed filtrates containing the nickel are placed in a tall beaker, and dilated if necessary to about 200 c.c. Ten c.c. of strong ammonia are added, and the solution, heated to 70 C., is ready for electrolysis. A battery of two 1-1/2 pint Bunsen cells is used. This is found capable of depositing from .15 to .20 gram of nickel per hour, and from two to three hours is generally sufficient for the electrolysis. The electrode with the deposited nickel is washed with distilled water, afterwards with alcohol as described under copper, and is then dried and weighed.

The following results obtained with this method by Mr. Hope illustrate the accuracy of the method. They were obtained by working on solutions containing known weights of the two metals:

- - Taken. Found. Cobalt. Nickel. Cobalt. Nickel. .1236 gram .1155 gram .1242 gram .1155 gram .1236 " .0577 " .1232 " .0575 " .2472 " .0577 " .2449 " .0585 " .3708 " .0577 " .3701 " .0580 " .0618 " .3465 " .0619 " .3454 " .0618 " .2310 " .0625 " .2295 " .0618 " .1155 " .0621 " .1155 "

FOOTNOTES:

[124] For fuller information see a paper on "The Estimation of Minute Quantities of Gold," by Dr. George Tate; read before the Liverpool Polytechnic Society, Nov. 1889.

[125] Journal of the Society of Chemical Industry, No 4, vol. ix. April 30, 1890.



APPENDIX C.

A LECTURE ON THE THEORY OF SAMPLING.

The problem of the sampler is essentially the same as that of the student of statistics. One aims at getting a small parcel of ore, the other a number of data, but each hopes to obtain what shall represent a true average applicable to a much larger mass of material. Ignoring the mechanical part of the problems, the sampling errors of the one and the deviations from the average of the other are the same thing.

It may be doubted whether many not specially trained in the study of statistics could answer such a question as the following:—Seven hundred thousand men being employed, there are, in a given year, one thousand deaths from accident. Assuming the conditions to remain unaltered, within what limits could one foretell the number of deaths by accident in any other year?

On the other hand, there is a widespread belief in the efficacy of what is called the law of averages. Even the ordinary newspaper reader is accustomed to look on the national death-rate or birth-rate as a thing capable of being stated with accuracy to one or two places of decimals, and he knows that the annual number of suicides is practically constant.

If a man played whist often and kept a record of the number of trumps n each hand, he would find fortune treated him quite fairly; in a year's play the average number would deviate very little from the theoretical average, i.e., one-quarter of thirteen. And a knowledge of this truth is useful, and that not merely in keeping ejaculations in due restraint. But every good player knows more than this: he has a sense of what variations in the number of trumps may reasonably be expected. For example, he will be prepared to risk something on neither of his opponents having more than five trumps, and will accept it as a practical certainty that no one has more than eight. Much of what is known as good judgment is based on a proper estimate of deviations from the average. The question has an important bearing on sampling, as may be seen from the fact that shuffling and dealing at cards are but modifications of the well-known mixing and quartering of the sampler.

Because of this bearing on sampling and for other reasons, I became many years ago much interested in the question, and gave to its solution perhaps more labour than it was worth. In books on Medical Statistics the answer to the question is stated in a mathematical formula, called Poisson's formula, which, in a modified form, I shall give further on. But this did not satisfy me, because I wanted to learn what a reasonably safe limit of error actually meant, and this could be best learnt by experiment; so with the help of some friends I went in for a thorough course of penny-tossing.

Tossing a penny twenty times, an average result would be ten heads and ten tails. To find the deviations from this, we tossed two hundred twenties, i.e., four thousand times. Of the two hundred, thirty-three gave the exact average, viz.:—10 heads; sixty-four gave an error of one, viz.:—9 or 11 heads; forty-nine, an error of two; twenty-six, an error of three; twenty, an error of four; eight gave an error of five, and this limit was not exceeded. From these we may say that six is a reasonably safe limit of error. Ninety-seven cases, say one-half, gave an error not exceeding one; and the mean error is 1.8.

In other words, in twenty tosses you will not get more than 16 nor less than 4 heads; you are as likely as not to get 9, 10, or 11 heads; and lastly, if you lost in twenty throws all heads or tails over 10 your average loss would be 1.8 penny, or say roughly 2d. on the twenty throws.

It was necessary to compare these with another series containing a larger average, say that of 100 heads in 200 throws. I confess the labour of tossing pennies two hundred at a time was little to our taste. So from a bag of pennies borrowed from the bank, we weighed out samples containing two hundred, and for an evening we were busy counting heads and tails in these. The heads in sixty samples ranged from 80 to 114. One hundred heads occurred seven times. The extent and frequency of the errors is shown in the table.

- - - Error. No. of Error. No. of Error. No. of Times. Times. Times. - - - 1 8 6 3 11 1 2 5 7 3 14 3 3 6 8 3 15 1 4 3 9 7 18 2 5 6 10 1 20 1

We may call the limit of error 21. Twenty-nine results out of sixty, say one-half, had an error not exceeding 4; and the mean error is 5.6. In comparing these with the series 10 in 20 we must, working by rule, divide not by 10 but by 3.16, the square root of 10; for if we multiply an average by any number[126] the error is also multiplied but only by the square root of the number. The error varies as the square root of the number. Now

21/3.16 = 6.6 = limit of error for 10 in 20. 5.6/3.16 = 1.8 = mean error " " " 4/3.16 = 1.2 = probable error " " "

It will be seen that these calculated results agree fairly well with those actually obtained. The rule by which these calculations are made is important and will bear further illustration. To calculate the number of heads in 3200 throws, we have to find the limit of error on a true average of 1600 in 3200. This being 16 times the average of 100 in 200, the corresponding errors must be multiplied by 4. This gives

214 = 84 = limit of error. 5.64 = 22.4 = mean error. 44 = 16 = probable error.

The results I have actually obtained with these large numbers are hardly enough to base much on, but have a value by way of confirmation. Expecting 1600 heads, the actual numbers were 1560, 1596, 1643, 1557, 1591, 1605, 1615, 1545.

It will be seen that exactly half are within the probable error; but this, considering the small number of results, must be more or less of an accident; it is more to the point they are all well within the limits of error.

I have a large number of other results which with a single exception are all in accord with those given; and this exception only just overstepped the limits. It was like a case of nine trumps, which though in a sense possible, is very unlikely to happen in any one's experience.

But even now we are not quite in a position to answer the question with which we started. If you refer to it you will see that we are face to face with this problem: the limit of variation on the 1000 who died would be say 70,[127] ignoring decimals. But if we calculate on the number who did not die, viz.—699,000,[128] we shall get a variation 26 times as great as this. But it is evident the variation must be the same in each case. I submitted this kind of problem also to the test of experiment, the results of which gave me great faith in Poisson's formula.

Imagine two hundred pennies in a bag all heads up. Any shaking will spoil this arrangement and give a certain proportion of tails. And, further, the probable effect of shaking and turning will be to reduce the preponderance of heads or tails whichever may be in excess. This of course is the reason why we are so unlikely to get more than 120 of them in either position.

But if the two hundred pennies are increased to 20,000 by adding pennies which have tails on both sides, then the shaking or mixing would be less effective. We should still expect as an average result to get the 100 heads but in 20,000 instead of 200. The variation will be 28 or 29 on the 100 instead of 20. And this is a better limit in such cases. Taking 28 as the limit of error on 100 instances and proportionally increasing the others so that the mean error becomes 7.8 and the probable error 5.6, we may now calculate the answer without gross mistake.

The probable variation on the 1000 deaths by accident will be 18, the mean variation will be 24.6, and the limits of variation 88.5. One such table showing in five years a mean number of deaths of about 1120 per annum gives an annual deviation of about 50 up or down of this. It will be seen at once that an improvement of 30 or 40 in any one year would be without meaning, but that an improvement of from 100 to 200 would indicate some change for the better in the circumstances of the industry. Before applying these principles to the elucidation of some of the problems of sampling it will be well to give Poisson's formula (in a modified form) and to illustrate its working.

Let x equal the number of cases of one sort, y the cases of the other sort, and z the total. In the example, z will be the 700,000 engaged in the industry; x will be the 1000 killed by accidents, and y will be the 699,000 who did not so die. The limit of deviation or error calculated by Poisson's formula will be the square root of 8xy/z. Replacing x, y and z by the figures of the example we get the square root of (81000699000)/700,000, which works out to the square root of 7988.57, or 89.3. Which means that we may reasonably expect the number of deaths not to vary from 1000 by more than 89, i.e., they will be between 1090 and 910. It will be seen that this number is in very satisfactory agreement with 88.5 given by the rougher calculation based on my own experiments.

To come to the question of sampling. Consider a powder of uniform fineness and fine enough to pass through an 80 sieve. For purposes of calculation this may be assumed to be made up of particles of about one-eighth of a millimetre across (say roughly 1/200 of an inch); cubed, this gives the content as about 1/500 (strictly 1/512) of a cubic m.m. Now one cubic m.m. of water weighs 1 milligram; therefore 500 such particles if they have the specific gravity of water weigh 1 milligram, and otherwise weigh 1 milligram multiplied by the sp. gr.: 500 particles of ruby silver (Pyrargyrite)[129] will weigh 5.8 milligrams and will contain nearly 3.5 milligrams of silver.

Now suppose a portion of 3.2667 grams (1/10 Assay Ton) of silver ore to contain 500 such particles of ruby silver and no other material carrying silver: such an ore would contain 35 ozs. of silver to the ton. But the limits of variation on 500 particles would be 28[130] multiplied by the square root of 5, or 62 particles. Thus the limit of sampling error would amount to just one-eighth of the silver present, or say to rather more than 4 ozs. to the ton; the mean sampling error would be rather more than a quarter of this, or say about 1.3 ozs. to the ton.

On the other hand, if one took for the assay a charge six times greater (say about 20 grams), the number of particles would be 3000 and the limits of variation would be 28 multiplied by the square root of 30, or 153 particles, which is very closely 1/20 of the silver present, or say 1.75 ozs. to the ton, whilst the mean error would amount to about .5 ozs. to the ton.

To work these examples by Poisson's formula let us assume the gangue to have a mean sp. gr. of 3. Then 500 particles would weigh 3 milligrams; and 3.2609[131] grams would contain 543,500 particles. There would be then 500 of ruby silver and 543,500 of gangue, together 544,000, and the formula gives the square root of (8500543500)/544000, which works out to 63 particles as against 62 by the other method.

A practical conclusion from this is of course that either the ore must be powdered more finely or a larger portion than 3 grams must be taken for the assay. Moreover, it is evident that on such an ore no small sample must be taken containing less than several million particles.

Consider now a copper ore of the same uniform fineness containing particles of copper pyrites (sp. gr. 4) of which 1000 particles will weigh 8 milligrams, mixed with gangue of which 1000 particles weigh 6 milligrams.

If one gram of such ore contain .5 gram of copper pyrites (= .1725 gram copper) and .5 gram of gangue, these will contain 62,500 and say 83,500 particles respectively. Altogether 146,000 particles. With Poisson's formula this gives the limit of sampling error as the square root of (86250083500)/146000 or 521 particles. But a variation of 521 on 62,500 is a variation of .83 per cent. The percentage of copper in the ore is 17.25 per cent., and .83 per cent. of this is .14 per cent. The limits of sampling error, therefore, are 17.11 per cent. and 17.39 per cent. Again, it must be remembered that the mean sampling error would be a little over one-quarter of this, or say from 17.2 per cent. to 17.3 per cent. The practical conclusion is that a powder of this degree of fineness is not fine enough. In the last place let us consider a similar iron ore containing 90 per cent. of hmatite (sp. gr. 5) and 10 per cent. of gangue (sp. gr. 3), 1 gram of such ore will contain 90,000 particles of hmatite weighing .9 gram and containing .63 gram of iron with say 16,500 particles of gangue weighing .1 gram. Altogether 106,500 particles.

Poisson's formula then gives the limits of variation as the square root of (89000016500)/106500 or 334 particles. But 334 on 90,000 is 0.23 on 63.0, which is the percentage of iron present. The limits of sampling error then are 62.77 per cent. and 63.23 per cent. and the mean variation is from 62.94 per cent. to 63.06 per cent.

These examples are worthy of careful consideration, and it must be remembered that the calculations are made on the assumption that the ore is made up of uniform particles of mineral of such fineness as would pass easily through an 80 sieve, but which does not pretend to represent with great exactness the fineness of the powdered ore customary in practice. They show that having passed through such a sieve is no proof of sufficient powdering, not that all ores powdered and so sifted are unfit for assaying. This last would be an absurd and illogical conclusion.

If an ore be powdered to a fairly fine sand and then be passed through a series of sieves, say a 40, 60, and 80, in such a state that little or none remains on the first, but the others retain a large proportion; then of that which comes through the 80 sieve, perhaps two-thirds by weight may be even coarser than the powder I have used in the example. Of the rest most may be of about half this diameter; the weight of the really fine powder may be quite inconsiderable. On the other hand, if the grinding be continued until, on sifting, little or nothing that is powderable remains on the sieves; then in the sifted product the proportions will be very different. This last, of course, is the only right way of powdering. Also it is evident that so much depends on the manner of powdering that nothing precise can be stated as to the average coarseness of the powder. Suppose, however, by good powdering a product is obtained which may be represented by a uniform powder with particles 1/20th of a millimetre in diameter (say roughly 1/500 inch). Compared with the previous powder, the diameter has been divided by 2.5; their number, therefore, in any given weight has been increased by the cube of 2.5, which is 15.6. But the value of a sample varies as the square root of the number of particles. Hence the reduction in size and consequent increase in number has made the sample nearly four times better than before; and it will be seen that this brings the sampling error within tolerable limits.

There are one or two words of warning which should be given. In the first place, using a 90 sieve instead of an 80 must not be too much relied on; the powder I took in the example would pass through it. It is a question of good powdering rather than of fine sifting. In the second place, a set of, say half-a-dozen, assays concordant within 1 oz. where the theory gives 4 ozs. as the limit of error does not upset the theory: the theory itself states this as likely. It is the error you may get in one or two assays out of a hundred, not the error you are likely to get in any one assay, which is considered under the heading "limit of error."

Accepting the result just arrived at that a portion of 1 gram may be safely taken for an assay if the particles are 1-20th of a millimetre in diameter, the further question remains as to what weight of the original sample must be reduced to this degree of fineness. This may be answered on the principle that the same degree of excellence should be aimed at in each of a series of samplings. This principle is illustrated in the table on page 2.

A fine sand, such as would pass a 40 sieve but be retained on a 60 sieve, would be fairly represented by particles one-quarter of a millimetre in diameter. This being five times coarser, to contain the same number of particles must be 125 times (the cube of 5) as heavy; therefore 125 grams of it can be taken with the same degree of safety as 1 gram of the finer powder. Of such a sand about this weight should be taken and reduced to the finer powder. If the ore were in coarse sand, say in particles 1 millimetre in diameter, this would be four times as coarse as that last considered, and we should have to take 64 times as much of it: 64 times 125 grams is 8 kilos, or say roughly from 15 to 20 lbs. This should be crushed to the finer size and mixed; then from 100 to 150 grams should be taken and ground to the finest powder.

There is, however, a reason why, on the coarser stuff, a smaller proportion may safely be used. This becomes more evident if we consider a still coarser sample. A heap of ore in stones about 2 inches across would be 50 times coarser than the sand, and an equivalent sample would need to be 125,000 times heavier; this would amount to about 1000 tons. Experienced samplers would say that under such conditions so large a sample was hardly necessary.

This is because I have assumed in the calculations that the grains of copper pyrites, for example, were all copper pyrites and the particles of gangue were free from copper. This would be true or nearly so for the very fine powder, but far from true in the case of the ore heap. In the heap probably few of the stones would be pure ore and still fewer would be free from copper. The stones would differ among themselves in their copper contents only within certain comparatively narrow limits. And it is evident that, if replacing one stone by another, instead of resulting in the gain or loss of all the copper one or other contained, merely affected the result to one-tenth of this amount, then a sample of 1-100th of the weight (say 10 tons) would be equally safe.

It should be remembered, however, that while the man who samples on a large scale can safely and properly reduce the size of his samples on this account, yet the principle is one which counts less and less as the stuff becomes more finely divided, and ought to be ignored in the working down of the smaller samples which come to the assayer.

FOOTNOTES:

[126] The 10 in 20 multiplied by 10 = 100 in 200.

[127] Multiply the errors for 100 by the square root of 10.

[128] Multiply the errors for 100 by the square root of 6990.

[129] Sp. Gr. 5.8. Silver 60 per cent.

[130] Taking 28 as the limit of variation on 100.

[131] The weight of the ore less the weight of ruby silver in it.



INDEX.

Acid measures, 49

Acidimetry, 323

Acidity of ores, 168

Acids, 54 strength of, 54, 75, 436

Air of mines, carbonic acid in, 428

Alkalies, 330 determination of, 331 Lawrence Smith's method for, 333, 412 separation of, 332

Alkalimetry, 323

Alkaline earths, 320

Alumina, 314 determination of, 315 in mineral phosphates, 316 separation of, 314, 316

Amalgamation, 126

Ammonia, detection of, 341 determination of, 342 in natural waters, 353

Antimony, 225 detection of, 227 dry assay for, 226 gravimetric assay, 228 separation of, 228 volumetric assay, 229

Arsenic, 381 detection of, 381 dry assay for, 382 gravimetric assay, 383 in brimstone, 393 in crude arsenic, 388, 393 in mispickel, 125, 392 iodine, assay for, 386 separation by distilling, 384 uranium acetate, assay for, 389 Volhard's method applied to, 124

Assay book, 11 note, 12 results, 7 tons, 13, 131

Assaying, 1 methods, 15

Assays, check, 154 preliminary, 147

Atomic weights, 69 table of, 433

Barium, 326

Baryta, 326

Barytes, sulphur in, 378

Base bullion, sampling of, 157

Basic acetate separation, 233

Baum's hydrometer, 77

Beryllia, 319

Bismuth, 220 colorimetric assay, 223 detection of, 221 gravimetric determination of, 222 in commercial copper, 208 separation of, 222

Black tin, 271 an analysis of, 287 assay of, 276 copper in, 204 examination of, 285 separation by vanning, 272

Blank assays, 34

Blende, sulphur in, 375 zinc in, 266

Book, assay, 11 laboratory, 10 sample, 9

Boracic acid. See Boron

Borax, examination of, 431

Boron, 429 direct determination of, 431

Brass, copper in, 194 zinc in, 265

Bromine and bromides, 361

Bronze, copper in, 194 tin in, 281

Burettes, 51

Burnt ore, silver in, 116, 118 sulphur in, 377

Cadmium, 269 gravimetric determination, 269 separation of, 269

Caesium, 339

Calcination, 22, 92, 139, 345

Calcium, 320 detection of, 321 gravimetric determination, 321 separation of, 321 titration with normal acid, 322 titration with permanganate, 322

Calculation of results, 7

Calculations from formul, 70

Calorific effect of coal, 419

Calorimeter, 419

Calx, 345

Carbon, 414 gravimetric determination, 416 in iron or steel, 423

Carbonates, 424

Carbonic acid in the air of mines, 428

Caustic potash = potassium hydroxide, 65

Caustic soda = sodium hydroxide, 66

Cerium, 318

Chalybite, iron in, 243

Charcoal, 21, 94

Check assays for gold, 154 for silver, 104, 113

Chlorine and chlorides, 359

Chromium, 307 gravimetric assay, 309 in chrome iron ore, 308 volumetric assay, 309

Clays, examination of, 316

Coals, 418

Cobalt, 259 detection of, 259 dry assay for, 251 gravimetric determination, 260 in hardhead, 288 separation from nickel, 442, 254, 258

Coke, 25

Common salt, examination of, 336

Concentrates, assay for gold of, 140

Colorimetric assays, 44

Copper, 175

Copper, bismuth in, 208 colorimetric assay for, 190, 203 commercial, arsenic in, 208, 388 commercial, copper in, 193 commercial, examination of, 205 cyanide assay for, 194 dry assay of, 176 dry assay, loss of, in, 176 electrolytic assay for, 190, 203 gold in, 206 iodide assay for, 199 iron in, 209, 249 lead in, 206 separation of, 183 silver in, 205 sulphur in, 207

Copper ores, solution of, 183 valuation of, 181

Copper pyrites, copper in, 179, 188, 198, 202 sulphur in, 376

Culm, 22

Cupel, 23, 142

Cupellation, loss, corrections for, 103 loss in gold, 145 loss in silver, 101 of gold lead alloys, 182 of silver lead alloys, 98, 110 temperature of, 143

Cyanicides, 169

Cyanide assay for copper, 194 for nickel, 255 for tin, 278

Cyanides, alkalinity of, 167 assay of, 167 commercial, 160 double, 161 gold-dissolving power, 162 prussic acid, 162 volumetric determination of, 163, 165

Cyanide liquors, alkalinity of, 167 assay of, 164, 165 assay of, for gold, 140 assay of, for zinc, &c., 169

Daniell cells, 185

Didymium, 319

Dollars to the ton, 9

Dry assays, 16

Drying, 5, 33

Earths, 314 the alkaline, 320

Electrodes, 187

Electrolysis for copper, 184 for nickel, 254

Equations, 69

Erbia, 319

Ferrous and ferric salts, 231

Filtration, 31

Finishing point, 42

Flasks, graduated, 49

Flatting, 149

Fluorine and fluorides, 363

Fluxes, 16, 93, 136, 138, 140

Formul, 68

Furnaces, 25

Galena, lead in, 217, 218

Gangue, 405 iron in the, 244

Gas-measuring apparatus, 52

Gases, measurement of, 44

Gay-Lussac's assay for silver, 119 assay for silver modified, 123

German silver, copper in, 194 nickel in, 255, 259

Gold, 126 amalgamation of, 126 in cyanide liquor, 140 loss of, in cupellation, 145 loss of, in parting, 154 preparation of, 63 silver in, 157 silver in, after parting, 154 test for, 126

Gold-lead alloys, cupellation of, 142 sampling of, 158

Gold ores assay with cyanide solutions, 141 calcination of, 139 concentrates, 140 fluxing, 136, 138, 140 sampling of, 127 size of assay charges, 127 tailings, 140

Gold-parting, 150 platinum in, 145, 154, 170, 171

Gold-zinc slimes, 142

Graduated vessels, 49

Gravimetric methods, 15, 27

Halogens, 358

Hardhead, 287 an analysis of, 289

Hot plate, 30

Hydrogen, preparation of, 62 reduction by, 280

Hydrometer, 77

Ignition, 32 in hydrogen, 280

Indicators, 42

Inquartation, 146

Iodine and iodides, 362

Iridium, 171

Iron, 231 bichromate assay for, 237, 243, carbon in, 423 colorimetric assay for, 247 ferrous and ferric, 231 gravimetric determination, 233 permanganate assay for, 236, 238 phosphorus in, 399 reduction of ferric solutions, 235, 241 separation of, 232 stannous chloride assay for, 244 volumetric assays for, 234

Iron ores, iron in, 244, 247 phosphates in, 399

Laboratory books, 9

Lanthanum, 319

Lawrence Smith's method for alkalies, 333, 412

Lead, 211 colorimetric assay for, 218 detection of, 211 dry assay for, 211 gravimetric determination of, 213 in commercial copper, 206 in commercial zinc, 214 in galena, 217, 218 separation of, 211, 213 volumetric determination of, 214

Litharge, use of, in dry assays, 20, 93

Lithium, 338

Lime, 320 milk of, 321 volumetric assays for, 322

Limestone, examination of, 329 lime in, 324

Limewater, 321

Loths, 9

Magnesia, magnesium, 328 mixture, preparation of, 64

Manganese, 298 colorimetric assay, 306 detection of, 299 gravimetric determination of, 300 separation of, 299 volumetric determination of, 300

Manganese peroxide, ferrous sulphate assay for, 301 iodine assay for, 302 = manganese dioxide, 298

Manganese ore, copper in, 204 manganese in, 300 peroxide in, 302

Matte, 18

Measuring, 49 flasks, 49 gases, 44, 52 gold buttons, 133, 440, liquids, 49 silver buttons, 106

Mechanical methods, 16

Mercury, 171 dry assay, 172 wet assay, 173

Metallic particles in ores, gold, 129 particles in ores, silver, 108 particles, tin, 278, 287

Micrometer, 133

Microscope, measuring with the, 440, 133

Mispickel, arsenic in, 125, 392 sulphur in, 376

Moisture, 7, 350

Molybdate separation for phosphates, 395 solution, preparation of, 60

Molybdenum, 311

Muffle, 25

Nessler's solution, 342

Nickel, 251 dry assay for, 251 electrolytic assay, 254 gravimetric determination of, 254 in German silver, 255, 259 separation from cobalt, 254, 258, 442 separation from iron, 258 separation from manganese, 258 separation of, 253 volumetric assay, 255

Niobium, 297

Nitre, 22 use of, in dry assays, 95

Nitrogen and nitrates, 400

Nitrometer, 403

Normal acid, normal solutions, 323

Ores, determining water in, 5, 351 drying, 5 powdering, 4, 109, 130, 448 quantities of, for an assay, 11, 27, 127 sampling, 1, 127, 444 with metallic particles, 3, 108, 129

Osmiridium, 171

Osmium, 171

Ounces to the ton, long, 107 to the ton, short, 132

Oxidation, 345

Oxides, 345 determination of oxygen in, 346

Oxidising agents, 22, 95, 345 effect of nitre, 95 effect of nitric acid, 56

Oxygen, 344 equivalent, 358 in natural waters, 344, 356 in ores, 348

Palladium, 171

Parting, 150 acids, 150 in flasks, 151 in glazed crucibles, 153 in special apparatus, 156 in test tubes, 152

Phosphate, assay of apatite for, 399 assay of iron ore for, 399

Phosphates, gravimetric assay, 396 volumetric assay, 397

Phosphorus and phosphates, 394 in iron, 399

Pipette, 50, 120

Platinum, 170 in gold, 145, 154, 170

Potash, commercial examination of, 338

Potassium, 336 gravimetric determination, 337

Potassium cyanide, 22, 65, 160 commercial assay of, 167 commercial, purity of, 161

Powdering, 4, 130, 448, 109

Precipitation, 30

Precipitates, drying, 32 igniting, 32, 34 washing, 31

Preliminary assays, 104, 147

Preparation of acids, 54 of other reagents, 59

Prill, 108, 129, 278, 287

Produce, 8

Pyrarsenate of magnesia, 383

Pyrites, iron in, 244 sulphur in, 370, 376

Pyrophosphate of magnesia, 397

Quantity to be taken for an assay, 11, 27, 127

Quartation, 146

Quartering, 2

Reagents, strength of, 54

Red lead for dry assays, 20, 22, 94

Reducing agents, 21, 94 effects of charcoal, &c., 94 effect of mineral sulphides, 95, 97, 98

Reduction by hydrogen, 280 of ferric solutions, 235, 242, 244

Regulus, 18

Report form, 12

Results, calculation of, 7, 13, 16, 38, 107, 131, 132 statement of, 7

Rhodium, 171

Roasting, 22, 345

Rolling, 149

Rubidium, 340

Ruthenium, 171

Sample book, 9

Sampling, 1 effect of powdering on, 449 errors, 447 gold ores, 127 metals, 157 theory of, 444

Scorification of silver ores, 88

Scorifier, 23, 89

Selenium, 379

Separation, as sulphides, 57 basic acetate, 233 molybdate, 395

Shales, bituminous, 420

Silicon and silicates, 405 in iron, 414

Silica in rocks, 409 in slags, 414

Silicates, alkalies in, 333, 412 beryllia in, 320 examination of, 409 titanium in, 411

Silver, 87 correction for cupellation loss, 103 detection of, 87 Gay-Lussac's assay, 119 Gay-Lussac's assay modified, 123 gravimetric determination of, 117 in bullion, 113 in burnt ore, 116, 118 in copper, 114, 205 in galena, 114 in lead, 113 in oxide of lead, 113 in silver precipitate, 115 loss in cupellation, 101 pure preparation of, 66 Volhard's assay, 121 volumetric methods, 119, 121, 123

Silver lead alloys, cupellation of, 98 sampling of, 157

Silver ore, crucible assay of, 90 metallic particles in, 108 scorification of, 88

Size of assay charges, 11, 27, 127

Slags, 19

Soda-lime, 425

Sodium, 334

Sodium cyanide, 160

Solution, 29

Solutions, normal, 323 standard, 36

Specific gravity, 75, 436

Speise, 19

Standard, 37 solutions, 36

Standardising, 37

Steel, carbon in, 423 chromium in, 310 manganese in, 300

Stoking, 25, 143

Strength of reagents, 54

Strontium, 324

Sulphates and sulphur, 367 gravimetric determination, 369 volumetric determination, 370

Sulphides, reducing action of, 9, 95

Sulphocyanate assay for silver, 121

Sulphur in blende, 375 in burnt ore, 377 in chalcocite, 376 in coal, 419 in copper, 207 in copper pyrites, 376 in mispickel, 376 in pyrites, 370, 376

Sulphuretted hydrogen, preparation, 57

Surcharge, 154

System in assaying, 28

Table, atomic weights, 433 comparing thermometers, 435 ounces to the long ton, 107 ounces to the short ton, 132 sp. g. ammonia, 438 sp. g. hydrochloric acid, 437 sp. g. minerals, 86 sp. g. nitric acid, 436 sp. g. sulphuric acid, 439 sp. g. water, 83

Tantalum, 297

Tartar, 20, 94

Tellurium, 379 improved test for, 150

Thallium, 219

Thorium, 317

Tin, 271 See also Black tin assay for, by vanning, 273 copper in, 204 Cornish assay, 276 cyanide assay, 278 detection of, 279 gravimetric determination of, 281 iron in, 250 separation of, 280 volumetric assay for, 282

Tin arsenide, 284

Tin phosphide, 284

Tin slag, 290 an analysis of, 292 tin in, 290

Titanium, 292 detection of, 293 in black tin, 272, 287 in rocks, 411 separation, &c., 294

Titration, 35 indirect, 43, 72

Ton, assay, 13, 131, long, 2240 lbs. = 32,666.6 oz., 107 short, 2000 lbs = 29,166.6 oz., 132

Tungsten, 295

Tungstic acid, 295 gravimetric determination, 296 in black tin, 285 in wolfram, 296

Uranium, 312

Valuation, of copper ores, 181

Vanadium, 310

Vanning, 273

Volhard's assay applied to arsenic, 124 silver assay, 121

Volume-corrector, 53

Volumetric assay, 35, 38

Water, 7, 350 direct determination of, 351 examination of, 352 expansion of, 83 solids in, 354

Weighing, 47 small gold buttons, 131

Weights, 47

Wolfram, an analysis of, 296 tungstic acid in, 296

Yttria, 319

Zinc, 261 commercial, examination of, 268 commercial, iron in, 249 commercial, lead in, 214 dry assay, 261 gasometric assay, 266 gravimetric determination, 262 in blende, 266 in cyanide liquors, 169 in silver precipitate, 266 separation of, 262 volumetric assay, 263

Zirconia, 317

Printed by BALLANTYNE, HANSON & Co.

London & Edinburgh.



A SELECTION FROM THE SCIENTIFIC AND TECHNICAL WORKS

PUBLISHED BY

CHARLES GRIFFIN & COMPANY, LIMITED.



MESSRS. CHARLES GRIFFIN & COMPANY'S PUBLICATIONS may be obtained through any Bookseller in the United Kingdom, or will be sent Post-free on receipt of a remittance to cover published price. To prevent delay, Orders should be accompanied by a Cheque or Postal Order crossed "UNION OF LONDON AND SMITH'S BANK, Chancery Lane Branch."

*** For INDEX, see next page. [Transcriber's Note: No index on next page.]



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THIRD EDITION, Revised, with an Additional Chapter on Foundations. Numerous Diagrams, Examples, and Tables. Large 8vo. Cloth. 16s.

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GENERAL CONTENTS.

Historical and Discursive.—Dock Design.—Constructive Appliances.—Materials.—Dock and Quay Walls.—Entrance Passages and Locks.—Jetties, Wharves, and Piers.—Dock Gates and Caissons.—Transit Sheds and Warehouses.—Dock Bridges.—Graving and Repairing Docks.—Working Equipment of Docks.—INDEX.

*** The object of the Author has been to deal fully and comprehensively with the problems arising out of the construction and maintenance of Docks and their appanages, not simply as a record of works carried out, but as a treatise on the principles underlying their construction and an investigation of the mathematical theories involved. It is primarily intended for the student; but it is hoped that the large amount of data and material collected from various sources, and in many cases contributed specially for this book, will render it useful to the expert engineer as a work of reference; while, at the same time, of general interest to directors and others connected with the management and administration of seaports.

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GENERAL CONTENTS.—Classification of different Types of Boilers—425 Experiments on English and Foreign Boilers with their Heat Efficiencies shown in Fifty Tables—Fire Grates of Various Types—Mechanical Stokers—Combustion of Fuel in Boilers—Transmission of Heat through Boiler Plates, and their Temperature—Feed Water Heaters, Superheaters, Feed Pumps, &c.—Smoke and its Prevention—Instruments used in Testing Boilers—Marine and Locomotive Boilers—Fuel Testing Stations—Discussion of the Trials and Conclusions—On the Choice of a Boiler, and Testing of Land, Marine, and Locomotive Boilers—Appendices—Bibliography—Index.

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* * * * *

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ENGINE-ROOM PRACTICE:

A Handbook for Engineers and Officers in the Royal Navy and Mercantile Marine, Including the Management of the Main and Auxiliary Engines on Board Ship.

BY JOHN G. LIVERSIDGE,

Engineer, R.N., A.M.I.C.E., Instructor in Applied Mechanics at the Royal Naval College, Greenwich.

Contents.—General Description of Marine Machinery.—The Conditions of Service and Duties of Engineers of the Royal Navy.—Entry and Conditions of Service of Engineers of the Leading S.S. Companies.—Raising Steam.—Duties of a Steaming Watch on Engines and Boilers.—Shutting off Steam.—Harbour Duties and Watches.—Adjustments and Repairs of Engines.—Preservation and Repairs of "Tank" Boilers.—The Hull and its Fittings.—Cleaning and Painting Machinery.—Reciprocating Pumps, Feed Heaters, and Automatic Feed-Water Regulators.—Evaporators.—Steam Boats.—Electric Light Machinery.—Hydraulic Machinery.—Air-Compressing Pumps.—Refrigerating Machines.—Machinery of Destroyers.—The Management of Water-Tube Boilers.—Regulations for Entry of Assistant Engineers, R.N.—Questions given in Examinations for Promotion of Engineers, R.N.—Regulations respecting Board of Trade Examinations for Engineers, &c.

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* * * * *

In Crown 8vo, extra, with Numerous Illustrations. [Shortly.

GAS AND OIL ENGINES:

An Introductory Text-Book on the Theory, Design, Construction, and Testing of Internal Combustion Engines without Boiler.

FOR THE USE OF STUDENTS.

BY PROF. W.H. WATKINSON, WHIT. SCH., M. INST. MECH. E., Glasgow and West of Scotland Technical College.

* * * * *

SECOND EDITION, Revised. With numerous Plates reduced from Working Drawings and 280 Illustrations in the Text. 21s.

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With a Section on American and Continental Engines.

BY ALBERT F. RAVENSHEAR, B.SC., Of His Majesty's Patent Office.

Contents.—Historical Introduction, 1763-1863.—Modern Locomotives: Simple.—Modern Locomotives: Compound.—Primary Consideration in Locomotive Design.—Cylinders, Steam Chests, and Stuffing Boxes.—Pistons, Piston Rods, Crossheads, and Slide Bars.—Connecting and Coupling Rods.—Wheels and Axles, Axle Boxes, Hornblocks, and Bearing Springs.—Balancing.—Valve Gear.—Slide Valves and Valve Gear Details.—Framing, Bogies and Axle Trucks, Radial Axle Boxes.—Boilers.—Smokebox, Blast Pipe, Firebox Fittings.—Boiler Mountings.—Tenders.—Railway Brakes.—Lubrication.—Consumption of Fuel, Evaporation and Engine Efficiency.—American Locomotives.—Continental Locomotives.—Repairs, Running, Inspection, and Renewals.—Three Appendices.—Index.

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* * * * *

In Large 8vo. Handsome Cloth. With Plates and Illustrations. 16s.

LIGHT RAILWAYS AT HOME AND ABROAD.

BY WILLIAM HENRY COLE, M. INST. C.E., Late Deputy-Manager, North-Western Railway, India.

Contents.—Discussion of the Term "Light Railways."—English Railways, Rates, and Farmers.—Light Railways in Belgium, France, Italy, other European Countries, America and the Colonies, India, Ireland.—Road Transport as an alternative.—The Light Railways Act, 1896.—The Question of Gauge.—Construction and Working.—Locomotives and Rolling-Stock.—Light Railways in England, Scotland, and Wales.—Appendices and Index.

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* * * * *

THIRD EDITION, Revised and Enlarged. With Numerous Illustrations. Price 8s. 6d.

VALVES AND VALVE-GEARING:

INCLUDING THE CORLISS VALVE AND TRIP GEARS.

BY

CHARLES HURST, Practical Draughtsman.

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"Almost EVERY TYPE OF VALVE and its gearing is clearly set forth, and illustrated in such a way as to be READILY UNDERSTOOD and PRACTICALLY APPLIED by either the Engineer, Draughtsman, or Student.... Should prove both USEFUL and VALUABLE to all Engineers seeking for RELIABLE and CLEAR information on the subject. Its moderate price brings it within the reach of all"—Industries and Iron.

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* * * * *

Hints on Steam Engine Design and Construction. By CHARLES HURST, "Author of Valves and Valve Gearing." In Paper Boards, 8vo., Cloth Back. Illustrated. Price 1s. 6d. net.

CONTENTS.—I. Steam Pipes.—II. Valves.—III. Cylinders.—IV. Air Pumps and Condensers.—V. Motion Work.—VI. Crank Shafts and Pedestals.—VII. Valve Gear.—VIII. Lubrication.—IX. Miscellaneous Details—INDEX.

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* * * * *

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For Engineering, Technical and Allied Trades.

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* * * * *

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Lubrication & Lubricants:

A TREATISE ON THE

THEORY AND PRACTICE OF LUBRICATION

AND ON THE

NATURE, PROPERTIES, AND TESTING OF LUBRICANTS.

BY LEONARD ARCHBUTT, F.I.C., F.C.S., Chemist to the Midland Railway Company,

AND

R. MOUNTFORD DEELEY, M.I.M.E., F.G.S., Midland Railway Locomotive Works' Manager, Derby.

CONTENTS.—I. Friction of Solids.—II. Liquid Friction or Viscosity, and Plastic Friction.—III. Superficial Tension.—IV. The Theory of Lubrication.—V. Lubricants, their Sources, Preparation, and Properties.—VI. Physical Properties and Methods of Examination of Lubricants.—VII. Chemical Properties and Methods of Examination of Lubricants.—VIII. The Systematic Testing of Lubricants by Physical and Chemical Methods.—IX. The Mechanical Testing of Lubricants.—X. The Design and Lubrication of Bearings.—XI. The Lubrication of Machinery.—INDEX.

"Destined to become a CLASSIC on the subject."—Industries and Iron.

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* * * * *

FOURTH EDITION. Very fully Illustrated. Cloth, 4s. 6d.

STEAM-BOILERS: THEIR DEFECTS, MANAGEMENT, AND CONSTRUCTION.

BY R.D. MUNRO, Chief Engineer of the Scottish Boiler Insurance and Engine Inspection Company.

GENERAL CONTENTS.—I. EXPLOSIONS caused (1) by Overheating of Plates—(2) By Defective and Overloaded Safety Valves—(3) By Corrosion, Internal or External—(4) By Defective Design and Construction (Unsupported Flue Tubes; Unstrengthened Manholes; Defective Staying; Strength of Rivetted Joints; Factor of Safety)—II. CONSTRUCTION OF VERTICAL BOILERS: Shells—Crown Plates and Uptake Tubes—Man-Holes, Mud-Holes, and Fire-Holes—Fireboxes—Mountings—Management—Cleaning—Table of Bursting Pressures of Steel Boilers—Table of Rivetted Joints—Specifications and Drawings of Lancashire Boiler for Working Pressures (a) 80 lbs.; (b) 200 lbs. per square inch respectively.

"A valuable companion for workmen and engineers engaged about Steam Boilers, ought to be carefully studied, and ALWAYS AT HAND."—Coll. Guardian.

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* * * * *

BY THE SAME AUTHOR.

KITCHEN BOILER EXPLOSIONS: Why they Occur, and How to Prevent their Occurrence. A Practical Handbook based on Actual Experiment. With Diagram and Coloured Plate. Price 3s.

* * * * *

JUST OUT. In Crown 8vo, Handsome Cloth. With Numerous Illustrations. 5s. net.

EMERY GRINDING MACHINERY.

A Text-Book of Workshop Practice in General Tool Grinding, and the Design, Construction, and Application of the Machines Employed.

BY

R.B. HODGSON, A.M. INST. MECH. E., Author of "Machines and Tools Employed in the Working of Sheet Metals."

INTRODUCTION.—Tool Grinding.—Emery Wheels.—Mounting Emery Wheels.—Emery Rings and Cylinders.—Conditions to Ensure Efficient Working.—Leading Types of Machines.—Concave and Convex Grinding.—Cup and Cone Machines.—Multiple Grinding.—"Guest" Universal and Cutter Grinding Machines.—Ward Universal Cutter Grinder.—Press.—Tool Grinding.—Lathe Centre Grinder.—Polishing.—INDEX.

"Deals practically with every phase of his subject."—Ironmonger.

* * * * *

FIFTH EDITION. Folio, strongly half-bound, 21/.

TRAVERSE TABLES:

Computed to Four Places of Decimals for every Minute of Angle up to 100 of Distance.

For the use of Surveyors and Engineers.

BY

RICHARD LLOYD GURDEN, Authorised Surveyor for the Governments of New South Wales and Victoria.

*** Published with the Concurrence of the Surveyors-General for New South Wales and Victoria.

"Those who have experience in exact SURVEY-WORK will best know how to appreciate the enormous amount of labour represented by this valuable book. The computations enable the user to ascertain the sines and cosines for a distance of twelve miles to within half an inch, and this BY REFERENCE TO BUT ONE TABLE, in place of the usual Fifteen minute computations required. This alone is evidence of the assistance which the Tables ensure to every user, and as every Surveyor in active practice has felt the want of such assistance FEW KNOWING OF THEIR PUBLICATION WILL REMAIN WITHOUT THEM."—Engineer.

* * * * *

WORKS BY

ANDREW JAMIESON, M. INST. C.E., M.I.E.E., F.R.S.E.,

Formerly Professor of Electrical Engineering, The Glasgow and West of Scotland Technical College.

* * * * *

PROFESSOR JAMIESON'S ADVANCED TEXT-BOOKS.

In Large Crown 8vo. Fully Illustrated.

STEAM AND STEAM-ENGINES (A Text-Book on). For the Use of Students preparing for Competitive Examinations. With 600 pp., over 200 Illustrations, 6 Folding Plates, and numerous Examination Papers. THIRTEENTH EDITION, Revised. 8/6.

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MAGNETISM AND ELECTRICITY (An Advanced Text-Book on). For Advanced and "Honours" Students. By Prof. Jamieson, assisted by David Robertson, B.Sc., Professor of Electrical Engineering in the Merchant Venturers' Technical College, Bristol. [Shortly.

APPLIED MECHANICS (An Advanced Text-Book on).

Vol. I.—Comprising Part I.: The Principle of Work and its applications; Part II.: Gearing. Price 7s. 6d. THIRD EDITION.

"FULLY MAINTAINS the reputation of the Author."—Pract. Engineer.

Vol. II.—Comprising Parts III. to VI.: Motion and Energy; Graphic Statics; Strength of Materials; Hydraulics and Hydraulic Machinery. SECOND EDITION. 8s. 6d.

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*** Each of the above volumes is complete in itself, and sold separately.

* * * * *

PROFESSOR JAMIESON'S INTRODUCTORY MANUALS.

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STEAM AND THE STEAM-ENGINE (Elementary Manual of). For First-Year Students. NINTH EDITION, Revised. 3/6.

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MAGNETISM AND ELECTRICITY (Elementary Manual of). For First-Year Students. FIFTH EDITION.. 3/6.

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* * * * *

IN PREPARATION. 300 pages. Crown 8vo. Profusely Illustrated.

MODERN ELECTRIC TRAMWAY TRACTION: A Text-Book of Present-Day Practice.

For the Use of Electrical Engineering Students and those interested in Electric Transmission of Power.

BY PROF. ANDREW JAMIESON.

* * * * *

A POCKET-BOOK of ELECTRICAL RULES and TABLES. For the Use of Electricians and Engineers. Pocket Size. Leather, 8s. 6d. SIXTEENTH EDITION. [See p. 49.

* * * * *

WORKS BY

W.J. MACQUORN RANKINE, LL.D., F.R.S.,

Late Regius Professor of Civil Engineering in the University of Glasgow.

THOROUGHLY REVISED BY

W.J. MILLAR, C.E.,

Late Secretary to the Institute of Engineers and Shipbuilders in Scotland.

* * * * *

A MANUAL OF APPLIED MECHANICS: Comprising the Principles of Statics and Cinematics, and Theory of Structures, Mechanism, and Machines. With Numerous Diagrams. Crown 8vo, cloth. SIXTEENTH EDITION. 12s. 6d.

* * * * *

A MANUAL OF CIVIL ENGINEERING: Comprising Engineering Surveys, Earthwork, Foundations, Masonry, Carpentry, Metal Work, Roads, Railways, Canals, Rivers, Waterworks, Harbours, &c. With Numerous Tables and Illustrations. Crown 8vo. Cloth. TWENTY-FIRST EDITION. 16s.

* * * * *

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* * * * *

A MANUAL OF THE STEAM-ENGINE AND OTHER PRIME MOVERS: With a Section on GAS, OIL, and AIR ENGINES, by BRYAN DONKIN, M.Inst.C.E. With Folding Plates and Numerous Illustrations. Crown 8vo, cloth. FIFTEENTH EDITION. 12s. 6d.

* * * * *

USEFUL RULES AND TABLES: For Architects, Builders, Engineers, Founders, Mechanics, Shipbuilders, Surveyors, &c. With APPENDIX for the use of ELECTRICAL ENGINEERS. By Professor JAMIESON, F.R.S.E. SEVENTH EDITION. 10s. 6d.

* * * * *

A MECHANICAL TEXT-BOOK: A Practical and Simple Introduction to the Study of Mechanics. By Professor RANKINE and E.F. BAMBER, C.E. With Numerous Illustrations. Crown 8vo, cloth. FIFTH EDITION. 9s.

*** The "MECHANICAL TEXT-BOOK" was designed by Professor RANKINE as an INTRODUCTION to the above Series of Manuals.

* * * * *

MISCELLANEOUS SCIENTIFIC PAPERS.

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With Memoir by Professor TAIT, M.A. Edited by W.J. MILLAR, C.E. With fine Portrait on Steel, Plates, and Diagrams.

"No more enduring Memorial of Professor Rankine could be devised than the publication of these papers in an accessible form.... The Collection is most valuable on account of the nature of his discoveries, and the beauty and completeness of his analysis.... The Volume exceeds in importance any work in the same department published in our time."—Architect.

* * * * *

SHELTON-BEY (W. Vincent, Foreman to the Imperial Ottoman Gun Factories, Constantinople):

THE MECHANIC'S GUIDE: A Hand-Book for Engineers and Artizans. With Copious Tables and Valuable Recipes for Practical Use. Illustrated. Second Edition. Crown 8vo. Cloth, 7/6.

* * * * *

SECOND EDITION, Revised and Enlarged. In Large 8vo, Handsome cloth, 34s.

HYDRAULIC POWER AND HYDRAULIC MACHINERY.

BY HENRY ROBINSON, M. INST. C.E., F.G.S.,

FELLOW OF KING'S COLLEGE, LONDON; PROF. OF CIVIL ENGINEERING, KING'S COLLEGE, ETC., ETC.

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* * * * *

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THE PRINCIPLES AND CONSTRUCTION OF PUMPING MACHINERY (STEAM AND WATER PRESSURE).

With Practical Illustrations of ENGINES and PUMPS applied to MINING, TOWN WATER SUPPLY, DRAINAGE of Lands, &c., also Economy and Efficiency Trials of Pumping Machinery.

BY HENRY DAVEY,

Member of the Institution of Civil Engineers, Member of the Institution of Mechanical Engineers, F.G.S., &c.

CONTENTS—Early History of Pumping Engines—Steam Pumping Engines—Pumps and Pump Valves—General Principles of Non-Rotative Pumping Engines—The Cornish Engine, Simple and Compound—Types of Mining Engines—Pit Work—Shaft Sinking—Hydraulic Transmission of Power in Mines—Valve Gears of Pumping Engines—Water Pressure Pumping Engines—Water Works Engines—Pumping Engine Economy and Trials of Pumping Machinery—Centrifugal and other Low-Lift Pumps—Hydraulic Rams. Pumping Mains, &c.—INDEX.

"By the 'one' English Engineer who probably knows more about Pumping Machinery than ANY OTHER.' ... A VOLUME RECORDING THE RESULTS OF LONG EXPERIENCE AND STUDY."—The Engineer.

"Undoubtedly THE BEST AND MOST PRACTICAL TREATISE on Pumping Machinery THAT HAS YET BEEN PUBLISHED."—Mining Journal.

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Royal 8vo, Handsome Cloth. With numerous Illustrations and Tables. 25s.

THE STABILITY OF SHIPS.

BY

SIR EDWARD J. REED, K.C.B., F.R.S., M.P.,

KNIGHT OF THE IMPERIAL ORDERS OF ST. STANILAUS OF RUSSIA; FRANCIS JOSEPH OF AUSTRIA; MEDJIDIE OF TURKEY; AND RISING SUN OF JAPAN; VICE-PRESIDENT OF THE INSTITUTION OF NAVAL ARCHITECTS.

In order to render the work complete for the purposes of the Shipbuilder, whether at home or abroad, the Methods of Calculation introduced by Mr. F.K. BARNES, Mr. GRAY, M. REECH, M. DAYMARD, and Mr. BENJAMIN, are all given separately, illustrated by Tables and worked-out examples. The book contains more than 200 Diagrams, and is illustrated by a large number of actual cases, derived from ships of all descriptions.

"Sir EDWARD REED'S 'STABILITY OF SHIPS' is INVALUABLE. The NAVAL ARCHITECT will find brought together and ready to his hand, a mass of information which he would otherwise have to seek in an almost endless variety of publications, and some of which he would possibly not be able to obtain at all elsewhere."—Steamship.

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THE DESIGN AND CONSTRUCTION OF SHIPS. By JOHN HARVARD BILES, M.INST.N.A., Professor of Naval Architecture in the University of Glasgow. [In Preparation.

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SECOND EDITION. Illustrated with Plates, Numerous Diagrams, and Figures in the Text. 18s. net.

STEEL SHIPS: THEIR CONSTRUCTION AND MAINTENANCE.

A Manual for Shipbuilders, Ship Superintendents, Students, and Marine Engineers.

BY THOMAS WALTON, NAVAL ARCHITECT, AUTHOR OF "KNOW YOUR OWN SHIP."

CONTENTS.—I. Manufacture of Cast Iron, Wrought Iron, and Steel.—Composition of Iron and Steel, Quality, Strength, Tests, &c. II. Classification of Steel Ships. III. Considerations in making choice of Type of Vessel.—Framing of Ships. IV. Strains experienced by Ships.—Methods of Computing and Comparing Strengths of Ships. V. Construction of Ships.—Alternative Modes of Construction.—Types of Vessels.—Turret, Self Trimming, and Trunk Steamers, &c.—Rivets and Rivetting, Workmanship. VI. Pumping Arrangements. VII. Maintenance.—Prevention of Deterioration in the Hulls of Ships.—Cement, Paint, &c.—INDEX.

"So thorough and well written is every chapter in the book that it is difficult to select any of them as being worthy of exceptional praise. Altogether, the work is excellent, and will prove of great value to those for whom it is intended."—The Engineer.

"Mr. Walton has written for the profession of which he is an ornament. His work will be read and appreciated, no doubt, by every M.I.N.A., and with great benefit by the majority of them."—Journal of Commerce.