214 Dr . Thomson on some of 
insoluble matter is obtained, quite similar in appearance to 
brown oxide of chromium. 
When we mix together solutions of chromate of potash 
and muriate of chromium, the mixture acquires the same 
brown colour, and a brown precipitate falls, evidently com- 
posed of chromic acid and green oxide of chromium. But 
this precipitate being soluble in water could not be edulco- 
rated, or freed from the foreign salts with which it was 
contaminated. 
8. Acetate of chromium. 
When strong acetic acid is digested in a flask over hydrated 
oxide of chromium, everal days elapse before any solution 
takes place, though the action be assisted by heat. By de- 
grees, however, the acid acquires a green colour, which gra- 
dually deepens. I was unable by this process to saturate the 
acid completely. The smell of acetic acid still continued 
strong, and the liquid had an acid, though sweet taste. This 
solution was evaporated to dryness in a low temperature. 
The matter which remained had a fine dark green colour, 
but it was insoluble in water, though a solution was again 
obtained by digesting it in acetic acid. 
Acetate of chromium then may be formed, but I was not 
able to obtain it in a state fit for analysis. 
9. Oxalate of chromium. 
Oxalic acid when digested over hydrated green oxide of 
chromium, dissolves it with considerable facility. The solution 
has a deep violet colour, and an excessively sweet taste. 
When evaporated to dryness it deliquesces again ; but if we 
