ON THE PURIFICATION OF CHLOROFORM. 
333 
results from the use of chloroform, so often spoken of else- 
where, it is enough to state that a large proportion of the cases 
must be attributed to the use of a liquid so impure as hardly 
to deserve the name of chloroform at all. 
Postscript. — Since writing the above, my attention has been 
called to a paper by Dr. Wilson, on the specific gravity of 
chloroform, which he was not able to obtain higher than 
1.498. I have therefore to add, that every specimen, whe- 
ther of specific gravity 1.4S0, 1.490, or 1.497, which I puri- 
fied as above, acquired the same density of 1.500, as ascer- 
tained by the use of a very delicate and accurate bead, (made 
by Lovi,) which sank at 60. °5 and rose at 59.°5 ; and also 
by three successive weighings with a very delicate balance. 
It will also be seen, that three commercial specimens had 
4 and 5, which symptoms are persistent, and occurred in my 
experiments always with an empty stomach, the experiments 
being made an hour or two before dinner. Mr. Carmichael, as- 
sistant to Dr. Simpson, has mentioned to me some facts which 
confirm the view 1 have taken. At one period, for more than a 
week, Dr. Simpson and Mr. Carmichael were kept in a state of con- 
tinual anxiety by the occurrence, in all the puerperal cases in which 
chloroform was used, of very unpleasant symptom?, particularly of 
frequent pulse and other febrile symptoms, lasting for some days. At 
last, after much annoyance from this cause, it occurred to Dr. Simp- 
son that he was using one particular specimen of chloroform above 
the average in quality. As soon as this idea occurred, he threw 
away all that remained, and returned to that which he had generally 
used. The unpleasant symptoms no longer appeared. [I regret 
much that I had not an opportunity of examining that specimen ; but 
I may add, that the maker, not an Edinburgh one, now produces 
chloroform of much better quality, though not yet absolutely pure.] 
But the striking fact is this, that Dr. Simpson and Mr. Carmichael 
state, that during the period above alluded to, when that one kind of 
chloroform alone was used by them, their handkerchiefs became 
quite offensive from the smell left on them, which even adhered to 
them after washing. There can, I think, be no doubt, that here the 
oily impurities alluded to in sections 4 and 5 were present in notable 
quantity. 
