204 
Dr. Thomson on some of 
We must attend to this circumstance, when we employ a 
benzoate to free a salt of chromium from iron. 
I. Muriate of chromium . 
Muriatic acid dissolves the hydrated green oxide of chro- 
mium with great facility ; but neither this nor any other acid 
answers as a solvent of anhydrous green oxide. Exposure 
to a red heat almost entirely destroys the solubility of this 
oxide. The muriatic solution has a very deep green colour, 
and always retains a great excess of acid. When evaporated 
to dryness, and kept for some time on the sand bath, much 
of this excess is driven off. The salt assumes a red colour 
and a scaly appearance. It still retains an excess of add 
and dissolves readily in water, forming a deep green liquid, 
having a sweet, and slightly acidulous taste. The scales 
rapidly absorb moisture from the atmosphere, and deliquesce 
into a green liquid. In this state the salt is composed of 
ij- atom muriatic acid - - 5' 781 
1 atom green oxide - - 5-000 
1 atom water - - - 1-125 
1 2-906 
If we raise the heat sufficiently high to drive of all excess 
of acid, and to convert the salt into a chloride, we obtain it 
in the form of light, tasteless, green scales. In this state it 
is insoluble in water and acids. I did not analyse it, but 
conceive it to be a simple chloride composed of 
3 atom chlorine - - 4*5 
1 atom chromium 4 
8-5 
