176 METHODS OF ANALYSIS 



until all the zinc sulphid, which should be pure white, is precipitated, filter upon a 

 tared Gooch and wash with hydrogen sulphid water, containing a little ammonium 

 nitrate. Dry the crucible and its contents in an oven, ignite at a bright red heat, 

 cool and weigh as zinc oxid. Calculate the weight of metallic zinc. 



BIBLIOGRAPHY. 



1 U. S. Bur. Chem. Circ. 102; J. Soc. Chem. Ind., 1907, 26: 1115. 



2 J. Assoc. Official Agri. Chemists, 1915, 1: 257. 



^Proc. Eighth Intern. Cong. Appl. Chem., 1912, 18: 35. 



