PHARMACEUTICAL SOCIETY, EDINBURGH. 
577 
it needs a few words regarding the olfactory part of it. It is only a very impure chloro¬ 
form that will leave , in the ordinary sense of the word, any unpleasant odour after its 
evaporation; and sometimes it happens that what is left, is of a rather pleasant flavour. 
And again, when chloroform, containing only a minute quantity of those deleterious oils 
formed with itself in the process of its preparation, is left to evaporate from a clean 
cloth or vessel, it is only at the last moment their offensive smell is felt; and if the sense 
of smell is not delicate and on the closest watch, it will not discover the taint, for it 
passes off instantly. 
We come now to the fourth test given, it “ evolves no gas when potassium is 
dropped into it.” 
About three weeks ago we got notice, from one of the most respectable houses in 
London, that the chloroform we had sent them did not stand the potassium test of the 
British Pharmacopoeia. From the first we held the test to be inapplicable, and such as, 
with the specific gravity given in the British Pharmacopoeia, ought not to be applied to 
it. We have the authority of Gregory and others that the specific gravity of pure 
chloroform is 1-500, and our own experiments assert the same thing. A specific gravity 
of 1-496, then, could only be the truth when the chloroform contained alcohol or water, 
or both ; and to admit into the Pharmacopoeia a chloroform containing those fluids, and 
then to apply a test for them, and reject the chloroform because they were present, 
seemed to us contradictory, and what could not have been the intention of the editors. 
We accordingly wrote our friends to the above purpose, and telling them that we did 
not believe any commercial chloroform could or would stand the test. It was thought 
well, however, to examine the matter a little more closely. 
A perfectly pure chloroform was very carefully prepared from alcohol by the process 
given in the B. P. Its specific gravity was 1-500 ; it gave no colour to S 0 3 ; left no re¬ 
sidue or odour of anything after evaporation, but it yielded gas with potassium. Spe¬ 
cimens of chloroform -were got from various makers, and others were prepared from 
acetone and methylated spirit, and one and all tried by the potassium test gave off" gas. 
At first the evolution of the gas was rapid, but very soon became slower, and a white 
crust was formed on the metal. On removing that crust the gas was again rapidly pro¬ 
duced. Sodium acted like potassium. The collection and examination of the gas pre¬ 
sents a number of difficulties not very easily overcome: the use of water is out of the 
question; mercury is liable to explosive amalgamation with the K or Na; other fluids 
present other incompatibilities with the necessities of the case, and we can only manage 
well when our pneumatic trough is filled with chloroform; and that, besides being 
rather an expensive fluid to work with, gives off its own vapour with the gas, and so 
complicates the result. 
The gas got by the action of Na on chloroform, and before washing it with water, burns 
with a yellow flame, somew'hat smoky, and sometimes with a tint of green at the edges; 
and mixed with about its own bulk of air and a light applied, it explodes with almost no 
violence, leaving sharp acrid acid fumes in the jar. A little water shaken with the vapour 
left in the jar after explosion is distinctly acid to litmus, and gives with AgNO.- 
abundant evidences of chlorine. On washing the gas with water some absorption takes 
place, and it then burns much more like Hydrogen, explodes more violently with air, and 
leaves less acid and chlorine in the jar. It is far too soon yet to say what the gas is or 
is not; so far as we have seen, however, it may be Hydrogen with the vapour of chloro¬ 
form diffused through it, and due to water, or alcohol, in the chloroform. But an ex¬ 
amination of the crust formed on the Na sets that aside, for it almost wholly consists of 
NaCl, which, under the circumstances, can only derive its chlorine from the decomposition 
of chloroform, or some other fluid containing chlorine mixed with the fluid called chloro¬ 
form, as that is got by the B.P. and other processes. That last supposition is not likely 
to be the truth, but whether it be so or not it still leaves potassium inadmissible as a 
test; for whatever the fluid is, it is produced according to the given formula. Our be¬ 
lief, however, is that chloroform is one fluid, and that it is decomposed both by Po¬ 
tassium and Sodium. 
How the error has arisen we cannot say, but the authors of the ‘ British Pharma¬ 
copoeia’ are not singular in their belief as to the non-evolution of gas from chloroform 
by the action of Potassium; for Liebig, as quoted in Gmelin, says that chloroform distilled 
over Potassium is not decomposed; and Heintz also, as quoted by Watts in his ‘ Dictionary 
of Chemistry,’ states that chloroform is not decomposed by Sodium even when heated with 
