582 
PHARMACEUTICAL MEETING. 
2N0Cl 2 + 3Ho0=z4HCl + HN0 3 +HIsr0 2 . 
Afterwards, assisted doubtless by daylight, the free chlorine oxidizes the greater 
part of the nitrous acid present, restoring it to its original condition of nitric 
acid. This part of the reaction, however, seems never to attain completion, 
but appears to be arrested at a certain point, which depends upon the degree of 
dilution. 
For the sake of comparison, some nitric and hydrochloric acids of the same 
strength were mixed with water in the phartnacopoeial proportion. Freshly 
prepared, the mixture seemed to contain no chlorine, but as time went on a 
certain amount was developed, which continued to increase, till, in less than a 
fortnight, the reactions furnished by this liquid coincided, as nearly as possible, 
with those obtained with the use of the officinal preparation. The amount of 
chlorinous constituent indicated in both cases is minute. The probability is, 
that in very dilute solutions, holding both nitric and hydrochloric acids, there 
is an atom of oxygen suspended, as it were, between the elements of nitrous 
acid, and those of the hydrochloric acid, giving rise, according to the concentra¬ 
tion of the liquid, to nitric acid and hydrochloric acid when extremely dilute; 
or to nitrous acid, water, and chlorine, when less of the diluent is present:— 
Hriro 2 
o 
H ci. 
H Cl. 
This sort of phenomenon occurs in numberless chemical decompositions, but at 
present can receive only a very imperfect kind of explanation. 
I feel justified, then, in adopting the two following conclusions :—first, that 
there is a loss in preparing nitro-hydrochloric acid, according to the plan of the 
present Pharmacopoeia, and that the solution obtained is consequently not con¬ 
stant in quality. I think it may be admitted, however, that the deficiency is 
for practical medicinal purposes insignificant. Secondly, that there is no pur¬ 
pose served in delaying the addition of the water, unless the diluted product has 
been quite recently prepared. In the absence of any experiments proving the 
superiority, from a therapeutic point of view, of the solution which is the result of 
this process, I should recommend that the acids be poured at once into the 
water in the proportions directed. It will be found that the product so obtained 
will answer to the tests indicated in the Pharmacopoeia more satisfactorily than 
that made by the official process, whilst as regards chemical constitution the 
lapse of a short interval will render it identical with that preparation. 
Dr. Redwood said he had made a great many experiments with this acid, 
some of the results of which accorded with those obtained by Mr. Tilden. The 
object of ordering the strong acids to be mixed some hours before diluting them 
with water was at once to obtain the product when mixed, in the state in which 
it was intended to be used. If the water was added to the strong acids before, 
or at the moment of, mixing them, a different result was obtained, and the 
product would not, in the first instance, contain free chlorine. This was shown 
by its not dissolving gold leaf, and, to the best of his recollection, it was neces¬ 
sary to keep it for two or three weeks before the required reaction took place, 
but no doubt this would in some degree depend on the extent to which it was 
exposed to direct sunlight. By following the instructions of the Pharmacopoeia, 
as soon as mixed it was ready for use. 
