48 URANIUM, ANTIMONY, CHROMIUM, &c. 



orange colour. It is very soluble in water, and 

 possesses the characters of a strong acid. 



1. The salts formed by the union of chromic 

 Chromates. acid and bases are called chromates. They have 

 a yellow or a red colour ; the chromates being 

 commonly yellow, and the bichromates red. 

 The bichromate of potash, being now used by 

 the calico printers, is manufactured in Glasgow 

 in very large quantities ; it is a salt of a fine 

 orange red colour, having a bitter and metallic 

 taste, and is much less soluble in water than the 

 , chromate of potash.* It contains no water of 

 crystallization, and as it bears a red heat with- 

 out decomposition, it may be easily freed from 

 all the water mechanically lodged between the 

 plates of the crystals. It has been demonstrated, 

 that in the bichromate of potash the quantity of 

 acid is just twice as much as in the chromate. 

 The bichromate reddens vegetable blues ; but the 

 chromate is neutral, and, consequently, a com- 

 pound of one atom chromic acid and one atom 

 potash. Of course, the bichromate is a com- 

 pound of two atoms chromic acid and one atom 

 potash. Either of these salts may be employed 

 to determine the atomic weight of chromic acid; 

 but the bichromate is much more easily pro- 

 cured in a state of purity, and therefore deserves 

 the preference. 



* For an account of the chromate and bichromate of potash, the reader 

 is referred to the Annals of Philosophy, XVI. 321. 



