[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.