Note 421 — Chapter XI · THE COPPER AND SILVER GROUPS. PRECIPITATION WITH HYDROGEN SULPHIDE
Reading edition
Noyes and Bray use, approximately, [H+] = 0.25 [J. Am. Chem. Soc., 29, 137 (1907)]. Tests in this laboratory showed that 1 milligram of cadmium-ion, or of lead-ion, in 100 c.c., is readily precipitated by hydrogen sulphide in the presence of 0.25 molar hydrochloric acid, ([H+] = 0.22).