SULPHUROUS ACID. 
517 
this body in various forms of disease seem to have been most successful; also 
used to some extent by Mr. Hamilton, Surgeon to the Liverpool Infirmary, 
in cases of typhoid or enteric fever ;* the results of whose experiments have 
been confirmed by Dr. Jones, of Liverpool.f The latter gentlemen both used 
a solution professedly of the Brit. Pharm. strength ; Dr. Dewar, a more dilute 
solution, not exceeding 4 per cent, of real sulphurous acid. 
For some time past I have observed that the solution of sulphurous acid, as 
supplied by manufacturers, variously labelled “ Sulphurous Acid, Saturated So¬ 
lution of Sulphurous Acid, Sulphurous Acid, B. P.” has very much differed 
from the acid as described by the Pharmacopoeia, which is defined as having a 
spec. grav. of T040, and containing 9*2 per cent, of real sulphurous acid. 
The commercial solutions I examined varied in strength from 2 to 6 per cent. ; 
none approached the high standard of the Pharmacopoeia. 
It was quite obvious that this deficiency did not arise from any attempt to 
make a preparation of inferior quality with such a body as sulphurous acid,—- 
used as it is daily in the arts in enormous quantity as a cheap bleaching agent, 
and moreover as in many laboratories it is merely a by-product,—but rather 
from some practical difficulties in making such a strong solution on the large 
scale. 
The following experiments were made with a view to determine the strength 
of the acid that could be obtained by the officinal process, and to ascertain the 
circumstances most favourable to its production :— 
1. Oil of vitriol was reduced in a flask by charcoal, the resulting gas after 
passing through the wash-bottle was allowed to slowly bubble through the water 
intended for its solution, this being kept at the temperature of the laboratory 
(65 9 to 70° F.) ; after 8 hours, nearly 2 per cent, was found to have been dis¬ 
solved, the solution having a spec. grav. of T009 at 60° F. 
2. The current of gas produced, as in previous experiment, allowed to pass 
slowly through water for 36 hours. Solution nearly 6 per cent.,, spec. grav. 
1-030. 
3. Gas passed through water slowly under a pressure of 1 lb. (2 inches mer¬ 
cury) for 8 hours, under same conditions as before. Solution 5 per cent., spec, 
grav. 1-028. 
4. Solution made under 2 lbs. pressure (4 inches mercury) for 8 hours, indi¬ 
cated 5| per cent. Spec. grav. T030. (This clearly showed the advantage of 
using pressure, the solution of the gas being more readily effected.) > 
5. Iced water \vas then kept around the receiver ; the gas was slowly passed 
through for 16 hours, resulting in a solution of nearly 9 per cent., and 1-045 
spec. grav. 
6. Increased pressure repeatedly tried, the result being invariably the fracture 
of the generator. 
Not having other available apparatus at hand, and as I had obtained much 
beyond the spec. grav. of the Pharmacopoeia solution, and had almost approached 
its strength,—from want of leisure I did not continue my research. 
The various solutions carefully examined^ with a volumetric solution of iodine 
of the strength indicated by the Pharmacopoeia, T X (T of an atom (12-7 grains) in 
1U00 grain-measures (the accuracy of the iodine solution being confirmed by the 
volumetric solution of hyposulphite of soda), gave results which, combined with 
* ‘ Lancet,’ vol. i. 1869, p. 45. 
+ Ibid. p. 126. 
X In weighing the acid for examination, I always counterpoised in the beaker in which the 
acid was to be weighed about one ounce of cold water, as I found this prevented the loss of gas 
of the strong solutions which invariably resulted if weighed alone, the acid being taken out 
with a pipette, the analysis of each specimen was thus effected rapidly—certainly in 3 or 4 
minutes. 
