ON THE PURIFICATION OF CHLOROFORM. 
331 
which destroys the oils and becomes brown, may be ob- 
tained after removing the sulphurous acid, of specific gravity 
1.500 at 60°. This I take to be the specific gravity of pure 
chloroform. Our best makers have lately, much to their 
credit, pushed the purification so far as to furnish chloroform 
even of this highest density, and also in other respects such 
as it ought to be. 
11. There are still, however, many makers in other places 
whose chloroform is not so pure ; and I shall now describe 
the method which, with Mr. Kemp, I have employed for 
purifying, perfectly and easily, any commercial chloroform, 
except one remarkable specimen — a process which will en- 
able any medical man to purify it for himself with the great- 
est facility. 
12. The chloroform, having been tested as above, and 
found more or less impure, is to be agitated with the oil of 
vitriol, (half its volume will be sufficient,) and allowed to 
remain in contact with the acid, of course in a clean, dry, 
and stoppered bottle, and with occasional agitation till the 
acid no longer becomes darker in colour. As long as the 
action is incomplete, there will be seen, after rest, at the line 
of contact, a darker ring. When this no longer appears, the 
chloroform may be drawn off, and for greater security once 
more acted upon by a quarter of its volume of the acid, 
which should now remain colourless. It is now to be once 
more drawn off, and in a dry stoppered bottle mixed with a 
little powdered peroxide of manganese, with which it is 
gently agitated, and left in contact until the odour of sul- 
phurous acid is entirely destroyed, and the chloroform has 
acquired a mild, agreeable, fruity smell. It has then only 
to be poured off into a proper phial. It will now leave no 
disagreeable smell when evaporated on the hand. [If the 
commercial chloroform, after having been frequently icell 
shaken and left for some time in contact with the acid, 
has given to it only a moderate tinge of colour, it is 
probable that it may be completely purified by the first 
