FOOTNOTES:
[9] Lead may be granulated by heating it to a little above the melting point, pouring it into a closed wooden box, and rapidly agitating it as it solidifies.
[10] A rod of iron placed in the crucible with the assays will decompose any regulus that may be formed.
[11] With buttons poor in silver the lowering of the temperature at this stage is not a matter of importance.
[12] 100 grams of the lead, or of its oxide, will contain from 1.5 to 2.5 milligrams.
[13] Still the precautions of having cupels well made from bone ash in fine powder, and of working the cupellation at as low a temperature as possible are very proper ones, provided they are not carried to an absurd excess.
[14] Be careful to remove the crucible before taking the bottle out of the basin of water; if this is not done the chloride may be washed out of it.
[15] 1 c.c. of this dilute acid will precipitate 8 or 9 milligrams of silver.
[16] Chlorides interfere not merely by removing silver as insoluble silver chloride, but also by making it difficult to get a good finishing point, owing to the silver chloride removing the colour from the reddened solution.
[17] These results were obtained when using ammonium sulphocyanate, and cannot be explained by the presence of such impurities as chlorides, &c.
[18] Multiply the standard by 1000, and dilute 100 c.c. of the standard solution to the resulting number of c.c. Thus, with a solution of a standard .495, dilute 100 c.c. to 495 c.c., using, of course, distilled water.
[19] HNa2AsO4 + 3AgNO3 = Ag3AsO4 + HNO3 + 2NaNO3.
[20]
SiO2 + Na2CO3 = CO2 + Na2SiO3
SiO2 + 2NaHCO3 = 2CO2 + Na2SiO3 + H2O.
[21] PbO + SiO2 = PbSiO3
[22] Here and elsewhere in this article when a flux is spoken of as soda the bicarbonate is meant.
[23] See the description of the process commencing on p. 98 and the explanatory remarks on p. 110.
[24] Percy, Metallurgy of Silver and Gold, p. 258.
[25] "Limits of Accuracy attained in Gold-bullion Assay," Trans. Chem. Soc., 1893.
[26] "Assaying and Hall-marking at the Chester Assay Office." W.F. Lowe. Journ. Soc. Chem. Industry, Sept. 1889.
[27] Fine or pure gold is 24 carat. Nine carat gold therefore contains 9 parts of gold in 24 of the alloy; eighteen carat gold contains 18 parts of gold in 24; and so on.
[28] The mouth of the flask must not have a rim around it.
[29] See "Assaying and Hall-marking at the Chester Assay Office," by W.F. Lowe. Journ. Soc. Chem. Industry, Sept. 1889.
[30] Percy, Metallurgy of Silver and Gold, p. 263.
[31] See also "The Assaying of Gold Bullion," by C. Whitehead and T. Ulke. Eng. and Mining Journal, New York, Feb. 12, 1898.
[32] Consult Percy's Metallurgy of Silver and Gold, p. 172; A.C. Claudet, Trans. Inst. Mining and Metallurgy, vol. vi. p. 29; G.M. Roberts Trans. Amer. Inst. Mining Engineers, Buffalo Meeting, 1898; J. and H.S. Pattinson, Journ. Soc. Chem. Industry, vol. xi. p. 321.
[33] Heycock and Neville, Journ. Chem. Soc., 1892, p. 907.
[34] G.M. Roberts.
[35] A.C. Claudet.
[36] "The Sampling of Argentiferous and Auriferous Copper," by A.R. Ledoux. Journ. Canadian Mining Institute, 1899.
[37] NaCNO + BaCl2 + NaHO + H2O = NH3 + BaCO3 + 2 NaCl.
[38] HCy + NaHO = NaCy + H2O.
[39] 2KCN + AgNO3 = KAg(CN)2 + KNO3.
[40] If it be desired to make a solution so that 100 c.c. shall be equivalent to 1 gram of sodium cyanide, then 18.085 grams of silver nitrate should be taken for each litre.
[41] AgNO3 + KAgCy2 = 2 AgCy + KNO3.
[42] AgNO3 + KI = AgI + KNO3.
[43] See pp. 322, 323, and 324 for a description of the methods for measuring the quantity of acid or alkali.
[44] KCN + HCl = KCl + HCN
[45] Taking 16.0 grams of ore, each c.c. = 1 lb. of soda to the short ton. The corresponding figures for the long ton are 12.544 grams for lime and 17.92 grams for soda.
[46] In which case each .01 gram of metal found equals 1 lb to the short ton of solution.
[47] 100 c.c. of water dissolves 0.66 gram of the salt; it is almost insoluble in alcohol or in solutions of ammonic chloride.
[48] According to Personne mercuric chloride is not volatilised from boiling solutions when alkaline chlorides are present.
[49] The solution should contain about 0.25 gram of mercury, and a large excess of nitric acid must be avoided.