576 
PHARMACEUTICAL SOCIETY, EDINBURGH. 
is C 4 II 4 CL. Somebody made a statement in Silliman’s American Journal that a 
solution in alcohol of the so-called chloric ether was a grateful stimulant. It led Mr. 
Graham to attempt making it cheaply by the action of bleaching powder upon 
alcohol; and believing lie had succeeded, he published his results, and gave a formula for 
its preparation in solution in alcohol. lie was, however, under a mistake ; what he did 
get was just an impure and somewhat weaker chloric ether of the present day,—that is 
to say, a solution of chloroform in alcohol, a solution of the compound C 2 II Cl 3 , and 
not, as he supposed, of C 4 H 4 CL. 
Soubeiran, in 1831, distilled bleaching powder and alcohol together; examining the 
product he discovered chloroform, and gave as its formula C II Cl or C, H 4 Cl 4 , and thus 
held it to be Thomson’s chloric ether plus another double atom of Cl, and therefore 
named it Bichloric ether. 
In 1832 Liebig also discovered and examined chloroform. He failed, however, to find 
hydrogen in it. Not much to be wondered at, as 119£ grains contain no more than one 
of Hydrogen. The formula given by him was C 4 Cl 5 , and he named it chloride of carbon. 
Dumas, in 1831, entered more carefully into its investigation, and as the result gave 
for its formula C 2 H Cl 3 , and named it by its present well-known designation, Chloro¬ 
form. Liebig, however, while he accepted Dumas’s formula, held it to be the perchlo- 
ride of the radical formule = C 2 H + Cl 3 and so named it the perchloride of formule. 
We may notice here that a compound with the same name differently spelt, said to be 
C 4 H 2 C1 4 is described in vol. ix.'of Gmelin’s Chemistry, pp. 199, 200, as ‘the so-called 
Perchloride of Formyl.’ 
Since Dumas’s investigation, and perhaps very properly following upon Professor 
Simpson’s discovery, almost the whole attention bestowed upon chloroform has been 
given to its ansesthetic properties, and its chemistry has been very nearly set aside. At 
this moment it has different names, and is variously formulated; its specific gravity is 
given by some as 1*484, and by others up to 1-500; the changes it undergoes by what we 
call spontaneous change, and by reagents, are either not at all or ill-understood, and the 
chemistry of its production from bleaching powder and alcohol, etc., is yet to be brought 
out. We need not wonder, therefore, that its characteristics and the tests given for its 
purity should be found somewhat amiss. The tests given in the British Pharmacopoeia 
are four—1st, the specific gravity 1496; 2nd, “not coloured by agitation with S0 3 ;” 
3rd, it leaves after evaporation no residue and no unpleasant odour; 4th, ‘ evolves no gas 
when potassium is dropped into it.’ It is to the last of these that your attention is to 
be more particularly called, but a few words upon the others may be advantageous. 
First, then, as to specific gravity. A perfectly pure chloroform will give a gravity of 
1-500, and perhaps a very little above that; but for a commercial article, well and care¬ 
fully manufactured, 1-496 is a perfectly fair standard. As it is sent out by manufacturers 
at present, we believe you will always find it to be from 1*498 to 1*500. Certainly 
anything below 1*496 ought to be held wrong. Here the editors of the ‘British 
Pharmacopoeia’ proceed upon a sound principle.; eschewing that myth, ‘absolute 
chemical purity,’ they allow a fair margin, and no more ; but, as we shall see, it should 
have been allowed all through. 
The second test, “not coloured by agitation with S0 3 ,” is unfortunately worded. An 
impure chloroform agitated with S 0 3 colours, and that deeply, the S 0 3 , while the chloro¬ 
form itself is left colourless, or all but colourless. It may be almost certainly held that 
what is meant is, that when agitated with S 0 3 , it gives no colour to the S 0 3 . “ Colour¬ 
less,” however, must be taken cum grano sails. A well-prepared chloroform will stand 
the test, provided the search for colour be made by transmitted light; but scarce any 
can be found which will not show a very faint tint in the S 0 3 , if a piece of white paper 
be put behind the tube. Moreover, the test requires precaution in its use. A somewhat 
dirty tube ; one cleaned with a woolly cloth, off which some fibres are left behind; the 
contact of the finger if employed to close the tube while agitating the fluids ; or some 
organic substance accidentally present,—will all give more or less colour to the acid. 
With the precautions mentioned, the S 0 3 test is a perfectly fair and most useful one. 
One other caution may be proper here, and that is, do not return the sample tested with 
S 0 3 to the stock; Chloroform twice treated with S 0 3 , Christison states, is likely to 
decompose. 
The third, that it “ leaves after evaporation no residue, and no unpleasant odour,” is, 
for the Pharmaceutical Chemist and the physician, the most important of them all; but 
