332 
ON THE PURIFICATION OF CHLOROFORM. 
process. To ascertain this, test a fresh portion in a tube 
with fresh acid, shaking well and allowing it to stand 
for some time. If it do not colour the acid at all, then 
the whole chloroform has only to be finally purified by the 
oxide of manganese. If the acid become coloured in the 
test-tube, it will be as well to act on the whole chloroform a 
second time with fresh acid till it stands the test. Mr. Kemp 
has observed, in repeating this process for me, the very cu- 
rious fact that, as soon as the action is complete, and the 
oily impurities are destroyed, but not sooner, the chloroform 
tested with the acid in a tube, exhibits a strongly convex 
surface downwards, where it rests on the pure acid, or what 
is the same thing, the acid becomes concave at its upper 
surface. The smallest trace of impurity, not sufficient to 
affect the density of the chloroform, we have found to ren- 
der the line of junction horizontal. It is probable that this 
may become a valuable test of the perfect purity of chloro- 
form ; but we shall not say more on this subject until we 
have thoroughly examined it.] This process requires no 
apparatus beyond a few stoppered bottles and a pipette, if we 
wish to draw off the whole chloroform without loss, although 
nearly the whole may be simply poured off. The use of the 
oxide of manganese is due to Mr. Kemp ; and on the large 
scale the chloroform may be filtered through a cylinder full 
of it. In this final purification of commercial chloroform, no 
distillation is necessary. Indeed, no rectification is required 
at all. if it be well washed with water before using the 
acid. 
13. It may be considered as certain, that the use of chlo- 
roform thus purified will very rarely, if ever, cause the dis- 
agreeable effects above noticed.* As to more serious bad 
* Dr. Simpson informs me, that the purest chloroform he 
has used not unfrequently causes vomiting. On further inquiries, 
I find that this occurs when it is administered, after a full 
meal. This can easily be avoided, and must not be confounded 
with the headache, nausea and vomiting alluded to in sections 
