2 atoms arsenic acid 

 1 atom potash 

 1 atom water 



22-625 



But there is almost always a little surplus water 

 (amounting to about half an atom) lodged me- 

 chanically between the plates of the crystals, 

 chromate, Q. Chromate of potash. This beautiful salt 

 contains no water of crystallization. Its consti- 

 tuents are 



1 atom chromic acid 6-5 



1 atom potash . 6 



12-5 



Biciiro- 10. Bichromate of potash. Neither does this 

 salt, the most splendid and one of the most use- 

 ful of the whole tribe of salts, contain any water 

 of crystallization. Its constituents are 



2 atoms chromic acid 13 

 1 atom potash . 6 



19 



Acetate, 11. Acetate of potash. This salt is so deli- 

 quescent that it is not easy to analyze it by the 

 usual methods j but the following experiment 

 comes sufficiently near to leave no doubt about 

 the quantity of water which it contains when in 

 crystals : 29*5 grains of protohydrate of acetic 



