COMPOSITION OF OXIDE OF ZINC. 53 



'very weak but pure nitric acid as was fully suf- 

 ficient to dissolve the whole zinc was introduced 

 into the retort. As soon as the metal was all 

 dissolved, a receiver was applied to the retort 

 which was placed in hot sand, and allowed to re- 

 main till the whole liquid contents had distilled 

 over. The liquid in the receiver was saturated 

 with carbonate of ammonia, and boiled for some 

 time to see whether it contained any zinc ; but 

 no precipitate appeared. 



The retort, thus freed from its liquid contents, 

 was placed upon a charcoal fire, and kept for 

 about an hour in a dull red heat. This com- 

 pletely decomposed the nitrate of zinc, which 

 existed at first in the retort, dissipated the 

 nitric acid, and left nothing behind but the 

 21*25 grains of zinc, now converted into an 

 oxide. Being placed in the scales, the zinc, by 

 being oxydized, was found to have increased in 

 weight 5 grains. Thus, it appears that oxide 

 of zinc is composed of 



Zinc 21-25 

 Oxygen 5 



26.25 ' 



or, dividing each constituent by 5 to bring them 

 to their lowest terms, of 



Zinc 4-25 

 Oxygen 1 



5-25 

 D3 



