OXYGEN AND HYDROGEN GASES. 



per cent, of water, while the British sulphate of 

 zinc contains 43-44 per cent. 



2. CARBONATE OF ZINC. 



One of the Experiments related while giving 

 the analysis of sulphate of zinc, is sufficient to 

 show the proportion of carbonic acid, which 

 combines with 5-25 parts of oxide of zinc. For 

 18-125 grains of sulphate of zinc, when decom- 

 posed by carbonate of soda, yielded a precipitate 

 which, after being well washed and dried in the 

 temperature of 212, weighed 8 grains, and 

 when exposed to a red heat, was reduced to 

 5*25 grains. These 8 grains were carbonate of 

 zinc. The carbonic acid was dissipated by the 

 red heat, and the oxide remained pure. We see 

 that 5-25 of oxide of zinc are converted into 

 carbonate by uniting with 2*75 grains of carbo- 

 nic acid. 



When carbonate of zinc is dried in the open 

 air,- without exposure to any artificial heat, I 

 have obtained it composed as follows : 



1 atom carbonic acid 2 '75 



1 atom oxide of zinc 5-25 



2 atoms water 2*25 



10-25 



so that an integrant particle of it weighs 10-25. 

 But the water is very easily dissipated indeed, 



