tS On the lest Method of decomposing 



The muriate is so far remarkable, that when evaporated 

 lo dryness, it gives a red powder which attracts humidity 

 iVonv the air; Us soUuion is of a fine green colour. If we 

 calcine it rather strongly, it gives out a smell of oxygenized 

 niuriaiic acid, acquires a great bulk, and is transferred into 

 small micaceous brilliant yellow fibres: finally, if we heat 

 it still more, it is totally converted into green oxide. 



We boiled several times, and in large quantities, nitric 

 acid over oxide of chrome recently precipitated, and it was 

 completely dissolved; but when we separated the oxide by 

 means of caustic potash, the supernatant liquor was co- 

 lourless : the contrary is the case when we evaporate to 

 dryness and slightly calcine: by redissolving in water, the 

 latter assumes a reddish colour ; and after the separation of 

 the oxide, the liquor remains of a fine golden yellow. 



We also dissolved oxide of chrome in phosphoric and in 

 oxalic acids: the first combination was of a splendid eme- 

 rald green colour, and the other, when viewed in the mass, 

 presented an amethyst hue. Sulphurous acid also dissolves 

 oxide of chrome with great facility. 



Action of the Caustic Alkalis on Oxide of Chrome, 



Tf into a solution of chrome a little diluted we ponf 

 caustic potash in a quantity above what is necessary for the 

 saturation of the acid, the oxide is redissolved in this aU 

 kali. We also obtain an alkaline solution of oxide of 

 chrome on taking it recently precipitated, diluting it with 

 a little water, and dissolving in this water some pieces of 

 caustic potash ; on afterwards diluting the combination 

 with water and filtering, we obtain a liquor of a fine green, 

 which, on ebullition, deposits the oxide it contains, and 

 the liquor remains colourless. 



Chromate of Potash. 

 There are two kinds of chromate of potash ; the one neu-* 

 tral is of a citron yellow, and crystallizes in small prisms. 

 This salt, on the addition of heat, assumes a fine red, but 

 xetufns to its natural colour when cooled. The second has 

 an excess of acid j its colour is orange-red, and it crystal- 

 lizes in beautiful prisms of the same colour. 



Chromate of Ammonia. 

 When we saturate ammonia by the chromic acid, an4 

 abandon the liquor to a spontaneous evaporation, an ar- 

 borescent salt is formed out of the liqucjr, composed of tufts 

 of fine yellow-: somelimes it is presented in the form of 



pearU 



