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 -Jths of its acid ; and 
almost -|th 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 so°o 6 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 
