ON THE PURIFICATION OF CHLOROFORM. 349 
afterwards, he says, « fortunately for Edinburgh and for 
chloroform — we may add, fortunately for suffering human- 
ity — the Edinburgh makers have always taken the best 
means and the greatest pains to produce good chloroform." 
The Professor gives what he calls a test of its purity, and 
"an easy mode of purification," which consists, in agitating 
the chloroform with sulphuric acid, and afterwards with 
peroxide of manganese. "It is then of specific gravity 1.500, 
and absolutely pure." The blackening of the sulphuric 
acid is a proof of impurity, and its absence the reverse. 
Now, Sir, I beg to caution your readers that the fact of 
any sample of chloroform having been manufactured in 
Edinburgh, is no proof of its purity ; and I would recom- 
mend them to apply another test in addition to the one sug- 
gested by the Professor. 
It is well known that the Scotch manufacturers having 
spirit much cheaper than it can be obtained in England, 
have a great advantage over the English makers of chloro- 
form. In February last, it was offered to me by one of the 
most respectable of the Edinburgh houses, at a price very 
much lower than I had ever before paid, and in consequence 
I obtained two Winchester quarts. It was professedly of 
the density 1.497. I found it about that, and I considered 
it good, though I thought it a shade less sweet than what I 
had been accustomed to use. 
Last month I found that it had acquired a suffocating 
odor, a greenish, oily-looking substance was deposited on 
the sides of the bottle, and the same appearance is evident in 
one of the bottles which is nearly full, and which has not been 
opened whilst in my possession, and has been kept in a 
dark cool closet. Moistened litmus paper suspended over it 
in a bottle was first reddened and afterwards bleached. Wa- 
ter with which it was washed indicated hydrochloric acid in 
considerable quantity. The bleaching I attribute to free 
chlorine, as I did not find sulphurous acid. It was unfit 
for respiration. -Sulphuric acid was but slightly discolored 
by it. 28 
