ON THE CHEMICAL PROCESSES AND PREPARATIONS. 
413 
test. Then, if we succeed in finding suitable oil of vitriol for the purpose, the 
distillation of the acid in glass retorts is a most difficult operation. The diffi¬ 
culty of concentrating oil of vitriol in glass was found to be so great, that manu¬ 
facturers gave it up, and took to the use of platinum stills at an enormous cost. 
Yet in that process the water is distilled away from the acid, while the concen¬ 
trated acid is left in the still. But in the Pharmacopoeia process we are directed 
to distil the acid itself. The apparatus for the purpose is before you, although 
I do not recommend you to undertake the operation. Manufacturers will, no 
doubt, be induced to do it at a price ; but then the question will very naturally 
be asked, Is the improvement in the product worth the cost of its production? 
By simple distillation the acid is deprived of a little sulphate of lead, which the 
commercial oil of vitriol contains, and which would be precipitated by merely 
diluting it with water, and by distilling it with sulphate of ammonia it is freed 
from any nitric or nitrous acids it may contain. Something more than this, how¬ 
ever, appears to have been contemplated in the process, for the product is de¬ 
scribed as monoliydrated sulphuric acid. Now will it realize this description when 
obtained by the process given ? I venture to say that it will not. It will not be 
monohydrated sulphuric acid, and this is perhaps a fortunate circumstance, for 
monoliydrated sulphuric acid would not be well suited for use in pharmacy. It is 
an acid which congeals in cold weather, as glacial acetic acid does, and the use of 
such an acid would be attended with much inconvenience. We are afforded a 
means of escape from this dilemma, it is true; for after stating that the sul¬ 
phuric acid to be used in medicine is to be the monohydrated acid, the descrip¬ 
tion goes on to say that it is to have a specific gravity of 1-846. Now this is 
the specific gravity of an acid weaker than the monohydrated acid. Still the 
specific gravity given is greater than it will be found easy to obtain, and the 
question again arises, Why should we be required to use a stronger acid than the 
acid of commerce, which is strong enough for any purpose to which it is applied 
in medicine ? 
Time will not admit of my entering further into the subject of the acids, 
and I therefore turn now to the alkalies. 
Liquor ammonite and liquor ammonite fortior are but little changed, yet they 
are not exactly as they were. The difference is so small that one wonders why 
there should be any difference. The specific gravities of the old and new solu¬ 
tions are as follows:— 
Pli. Lond. Pli. Brit. 
Liquor ammonia?. 0*960 ... 0*959 
Liquor ammoniae fortior. 0*882 ... 0*891 
Liquor potasses and liquor socles are both rather weaker than they were. In 
liquor potassae the difference is so small that it is hardly worth notice, but in 
liquor sodre there is a greater difference. The specific gravities of the old and 
new solutions are as follows *.— 
Pk. Bond. Pk. Brit. 
Liquor potassae. 1*063 ... 1*058 
Liquor sodae. 1*061 ... 1*047 
The two solutions, according to the London process, were made to nearly coin¬ 
cide in density ; whereas according to the new process they differ in density, 
but nearly coincide in neutralizing power. 
Potasses carbonas must be described as one of the new preparations of 
the British Pharmacopoeia. Hitherto the term “carbonate of potash” has 
been applied in our Pharmacopoeia to that very well known commercial ar¬ 
ticle commonly called “salt of tartar,” for the preparation of which a pro¬ 
cess was given in the London Pharmacopoeia of 1836. The process then 
given, and which is practically adopted on the large scale, consists in purifying 
VOL. v. 2 ¥ 
