NOTE ON SULPHUROUS ACID. 
217 
Ten samples of “ Liquor Sodsc Chloratse, B.P.” were also tested for chlo¬ 
rine, by the published formula, i. e. 70 grains (by weight) of the liquid with 
20 grains of iodide of potassium in 4 ounces of water, acidulated with hydro¬ 
chloric acid, were tested with the volumetric solution of hyposulphite of so¬ 
dium, B.P. As will he seen from the table, only 3 specimens required any¬ 
thing approaching to the prescribed amount (500 grain-meaures) of hypo¬ 
sulphite for the decolorization of the solution. 
III. 
Table Showing Variations of Commercial “ Liq. Socles Chlor.” 
(10 Samples.) 
No. of 
Grs. of test 
No. of 
Grs. of test 
Sample. 
Solution required. 
Sample. 
Solution required. 
1 . . . 
6 . . . 
.450 
2 . . . 
.510 
rr 
i 
.485 
3 . . . 
.395 
8 . . . 
4 . . . 
.370 
9 . . . 
.290 
5 . . . 
.420 
10 . . . 
.4S0 
Although not so ordered, Liq. Sodce Chlor. is frequently made from chlo¬ 
rinated lime and carbonate of sodium by double decomposition, a proceeding 
which sufficiently accounts for the extreme variation in strength observed. 
NOTE ON SULPHUROUS ACID. 
BY WENTWORTH LASCELLES SCOTT, E.C.S., ETC. 
Having had some little experience in relation to the manufacture of the 
above acid, both in quantities of a few ounces, and upon a very extensive 
plan, I can scarcely corroborate those contributors to the ‘ Pharmaceutical 
Journal ’ who have spoken of the extreme difficulty of preparing " sulphurous 
acid, B. P.” I have recently superintended the erection of some apparatus 
for the production of the acid upon rather a large scale, at the works ol: a 
well-known manufacturing firm,* and, except in some minor details, the 
arrangements present no particularly novel points. 
A uniform pressure of 3 lbs. per square inch is maintained by means of a 
water-column, and the process goes on continuously, the acid in the first 
receiver-jar being drawn off when sufficiently strong, and its place occupied 
by the weaker fluid contained in the last jar of the series; this, in its turn, 
being refilled with distilled water. As only the purest and most compact 
varieties of carbon are permitted to be used in the retort, which is of cast 
iron, and constructed specially for the purpose, the stoppages for clear¬ 
ing out, etc., are few and far between. Oil of vitriol, containing /4 per cent, ol 
anhydrous acid, is found more convenient in practice than either a weaker or 
stronger variety ; as when too concentrated acid is employed, a portion of it is 
liable to entire reduction, and sulphur incrustations are formed in unpleasant 
abundance, while, upon the other hand, a dilute vitriol causes the evolution 
of sulphuretted hydrogen. A little carbonic oxide is generall} 7 'to be de¬ 
tected amongst the gases evolved, but its presence is in no degree objection- 
able. # . . 
For washing the gas, simple water is of course sufficient, but the addition 
of some sulphite of lead, and a few pieces of charcoal, gives a purer acid. I 
* William Bailey and Son, Wolverhampton. 
VOL. XI. Q 
