[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] HNa_{2}AsO_{4} + 3AgNO_{3} = Ag_{3}AsO_{4} + HNO_{3} + 2NaNO_{3}. [20] SiO_{2} + Na_{2}CO_{3} = CO_{2} + Na_{2}SiO_{3} SiO_{2} + 2NaHCO_{3} = 2CO_{2} + Na_{2}SiO_{3} + H_{2}O. [21] PbO + SiO_{2} = PbSiO_{3} [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.