514 
PHAKMACEUTICAL MEETING. 
if it be properly adjusted at the commencement, and the process will often 
go on to the end without a variation of more than one or two degrees of tem¬ 
perature. When about twelve fluid ounces of liquid have been distilled the 
action will slacken, in consequence of tho exhaustion of the nitric acid, and 
this will be immediately indicated by the disappearance of the froth on the 
surface of the liquid. The suddenness with which this usually takes place is 
remarkable. It is followed by a rise of temperature in the liquid, if the ap¬ 
plied heat remain unaltered, but when the temperature reaches 180® the heat 
should be withdrawn, and the contents of the retort allowed to cool. There 
will still be a portion of the spirit left in the retort, together with sulphuric 
acid, sulphate of copper, and undissolved copper, and it is for the purpose of 
converting this spirit into nitrous ether that the remaining half-ounce of nitric 
acid is directed to be added. When this addition has been made the distil¬ 
lation is to be resumed as before, until the distilled product amounts to 15 fluid 
ounces. This product consists of a strong spirituous solution of nitrous ether 
containing thirty-five per cent, of the crude ether. On mixing it with the re¬ 
maining two pints of spirit, it will have the strength indicated in the British 
Pharmacopoeia of 1864, and will nearly answer to the other tests and charac¬ 
ters there given. The specific gravity will be 0'845. If it be mixed with 
twice its volume of a concentrated solution of chloride of calcium, from two 
to three per cent, of nitrous ether will separate and rise to the surface of the 
liquid. This indicates the presence of ten per cent, of ether, as eight per 
cent, remains unseparated. 
Spirit of nitrous ether made in this way, is, I believe, equal in every 
respect to that produced by any of the previously adopted processes, and it 
is better and stronger than most of what is met with in commerce. It is 
much stronger than that made by the London process, although the quantity 
of nitric acid employed in its production is less than one-half, and the loss of 
spirit is less than one-third, what they are in that process. It is therefore 
a very economical method of preparing the product; in fact it surpasses all 
the other processes in this respect, as there is no avoidable loss of nitric acid 
or alcohol, and the copper which is dissolved is recovered as sulphate of 
copper. Only about half the quantity of copper used, however, is thus dis¬ 
solved ; that which remains may be employed in a subsequent operation. 
But the principal recommendation to the process is that it affords the means 
of obtaining spirit of nitrous ether, on the large or small scale, of definite 
and uniform strength and composition, and of perfectly good quality. As 
these objects can be thus attained with ease and certainty, without any 
increase, but rather at a reduction, of cost, there will be no excuse for any 
other variation in the product than such as may arise from the change which 
necessarily takes place to some extent when it has been long kept in contact 
with the air. 
Having now explained the practical details of this process, I shall not pur¬ 
sue the subject further on the present occasion, but reserve for a subsequent 
communication the notice of some points in connection with it, the investiga¬ 
tion of which I have not yet completed. 
The Chairman, in expressing the thanks of the meeting for this communi¬ 
cation, remarked that it related to a preparation extensively used in medicine, 
but which had always been very uncertain in its strength and composition, 
and had frequently been the cause of complaint against those who supplied it 
in what was considered to be an improper state. The process, which they 
had all had an opportunity of witnessing,* appeared to be a very good and a 
* During the reading of tho paper the process was put into operation before the meeting. 
