SULPHUROUS ACID. 
519 
cumstances, be made without great difficulty (using copper and sulphuric acid 
to obtain the sulphurous acid) ; for we have the unquestionable authority of 
Bunsen upon the subject, who is thus cited by Miller, in his ‘ Elements of Che¬ 
mistry —“ Water will absorb at 32° F., 68'8 volumes; at 59°, 43‘5 volumes ; 
and at 75°, 32 volumes.” 
Now the Pharmacopoeia solution (which is about 37 volumes) was designedly 
made nearly one of saturation at the average summer temperature of this countr} 1- , 
and, if one may be excused for making a guess, was described from calcu¬ 
lations made from the above data of Bunsen’s, and not practically worked out to 
see whether such a solution could be ordinarily obtained in the manufacturing 
laboratory without chance of failure, and, when made, be kept without great 
alteration in the various stages it would have to pass through, even if only from 
the manufacturer to the wholesale druggist, then to the pharmacist, in whose 
store it might remain for a year or more, being perhaps placed in a temperature 
many degrees above the point at which it was saturated, thereby causing ex¬ 
pansion, liberation of gas, and inconvenience. 
It may be here worthy of note, that a solution of sulphurous acid of any great 
strength decomposes into sulphuric acid in partially filled bottles four times as 
rapidly in a light green bottle as when kept in one of dark blue,—the maximum 
rate being in six months equivalent to 1-436 per cent, sulphuric acid. The 
following table will give, I think, sufficiently accurate for medicinal purpo'ses, 
the specific gravity of solutions* from 1 to 8 per cent., made by the officinal 
process:— 
Per cent. 
Specific 
Volumetr. Sol. 
of S0 2 . 
gravity. 
. . . 1-005 . 
of Iodine, B.P. 
. . . 108-6 
1 . 
2 . 
. . . 1-011 . 
. . . 217-3 
3 . 
. . . 1-017 . 
... 326 
4 . 
. . . 1022 . 
. . . 434-6 
5 . 
. . . 1027 . 
. . . 543-3 
6 . 
. . . 1032 . 
... 652 
7 . 
. . . 1-037 . 
. . . 760-8 
8 . 
. . . 1-042 . 
. . . 869-5 
The stronger solutions are most powerful, causing not a little inconvenience 
in transfer from one bottle to another, from the quantity of irrespirable gas given 
off; and it is to be doubted, had an acid been used of Brit. Pharm. strength, or 
even one approaching it, in the experiments of Mr. Hamilton and Dr. Jones, 
as described in the ‘ Lancet,’ whether one-drachm doses to children and three- 
drachm doses to adults, every four hours, could have been given without ill 
effects. It is more probable that a solution, as ordinarily found in pharmacy, 
of about 2 or 3 per cent, was used. 
I should suggest that a solution of 1-027 specific gravity, containing 5 per 
cent, by weight of real acid, be substituted for the present officinal solution 
at the earliest opportunity, such a solution being sufficiently strong for me¬ 
dicinal purposes. There would then be no difficulties attendant upon the pro¬ 
duction of acid of such strength, neither would there be the least justification 
for the entire absence of such a solution from pharmacy. 
We should thus be giving the remedy a fair trial, and by its medicinal 
merits alone it would either retain its place or be expunged from future Pharma¬ 
copoeias. This communication, I trust, will prevent any blame from being 
attached to the pharmacist, if such a valuable remedy should undeservedly be 
brought into disrepute. 
Laboratory , 40, Aidersgate Street , E.C. 
* Made by dilution of the stronger solutions with water. 
