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the compounds of chromium. 
binarseniate of chromium. It was tasteless, and insoluble in 
water. When heated to redness it became rose red, but on 
cooling the colour became a dingy buff. This salt was 
analyzed in the following way. 
Six grains by ignition lost 1*45 grains, which were consi- 
dered as water. 12 grains were dissolved in caustic potash, 
and the alkali being neutralized by muriatic acid, the green 
oxide of chromium was thrown down by carbonate of am- 
monia. The precipitate dried on the filter weighed 4‘3 
grains : but by ignition the weight was reduced to 2-18 grains. 
Hence the constituents were 
Arsenic acid 
Green oxide of chrome 
Water 
6 92 or 15 8 
2* 18 or 5 
2-90 or 6-65 
12*00 
If we consider it as a compound of 2 atoms acid, 1 atom 
green oxide, and 6 atoms water, the constituents will be 
2 atoms arsenic acid 
1 atom green oxide 
6 atoms water 
1 5’5 
5 
6*75 
27-25 
numbers which approach very near the actual result of 
analysis. 
7. Chromate of chromium. 
When chromic acid is digested on hydrated green oxide of 
chromium, a solution takes place, and the liquid assumes a 
dark brown colour. When we dissolve as much of the oxide 
as possible, and evaporate the solution to dryness, a brown 
