208 
Dr. Thomson on some of 
redness lost 9*97 grains of their weight, and when kept for 
ten minutes in a wind furnace, in a heat approaching to 
whiteness, the weight was reduced to 8*58 grains. 20 grains 
(as is evident from the preceding analysis) of this salt con¬ 
tain 7'26 grains of green oxide. The salt, after exposure to 
an incipient red heat, retained nearly l-ths of its acid; and 
almost -Ith of the acid was retained after the strong heat of a 
wind furnace. I was unable by heat to bring sulphate of 
chromium to the state of green oxide. 
4. Carbonate of chromium. 
When muriate of chromium is precipitated by carbonate of 
soda, and the precipitate, after being well edulcorated, is 
collected on a filter, and dried in a heat not exceeding 212®, 
we obtain a light blue-coloured matter, which is very light, 
tasteless, and insoluble in water. In this state it is a dicar¬ 
bonate of chromium composed of 
1 atom carbonic acid - - 2-75 
2 atoms green oxide of chrome 10 
4 atoms water _ _ - 4-5 
17-25 
I exposed 30-06 grains of this dicarbonate to a strong red 
heat. The loss of weight was 12-9 grains. The same quan¬ 
tity being dissolved in nitric acid effervesced, and lost 4*6 
grains. This experiment requires some care, for the solu¬ 
tion does not take place without the application of heat. Thus 
the constituents of the salt were found to be 
