431 



and again treated with sulphuretted hydrogen ; the zinc then thrown 

 down by carbonate of soda and weighed as oxide. 



Analyses of the Lead-zinc Alloys. 



Bismuth-Zinc Alloys. 



The Bismuth-end. About 3 grms. were dissolved in nitric acid, 

 evaporated with hydrochloric acid to destroy the nitric acid, precipi- 

 tated by sulphuretted hydrogen, evaporated almost to dryness, and 

 again treated with sulphuretted hydrogen ; the zinc was lastly preci- 

 pitated by carbonate of soda and weighed as oxide. The analyses 

 marked (*) were made in the following manner : The alloy was dis- 

 solved in nitric acid, diluted with water, and the bismuth precipitated 

 by ammonia and carbonate of ammonia. The bismuth was filtered 

 off and washed with a mixture of 10 parts water, 2 of ammonia, and 

 1 of carbonate of ammonia. The filtrate was mixed with carbonate 

 of soda in excess, and evaporated down on a water-bath in a platinum 

 dish ; when dry, it was moistened with water and again evaporated to 

 dryness in order to drive off the last traces of ammoniacal salts. 

 The dry mass was then washed into a beaker, made slightly acid, 

 boiled, and whilst boiling precipitated by carbonate of soda : the zinc 

 was weighed as oxide. 



