REPORT ON NITRIC AND NITRO-HYDROCHLORIC ACIDS. 
169 
considerable quantity of nitrous acid, as evidenced when the acid is poured into 
water with a view to dilution ; that it is uncertain in strength, from its ten¬ 
dency to decompose, and that it is inconvenient to pack, dangerous in transit, 
and unmanageable in use. The acid of the British Pharmacopoeia of 1867 is 
doubtless an excellent substitute, containing, as it does, 70 per cent, of real acid. 
It undergoes no change on keeping. 
Referring to the second inquiry, — the nitro-hydrochloric acid, and the 
changes in it on keeping,—it is to be observed, that since the institution of 
these experiments, the British Pharmacopoeia of 1867 has been presented, with 
an alteration in the formula and directions for the production of this acid, and 
as it differs materially from that adopted in the previous publication,—that of 
1864,—I subjoin the two formulae for comparison. 
Acidum Nitro-hydrochloricum Dilutum. B.P. 1864. 
Nitric acid, sp. g. P5.2 fluid ounces. 
Hydrochloric acid, sp. g. 1T70 . . . 4 fluid ounces. 
Distilled water.26 fluid ounces. 
Add to the water, first the nitric acid, and then the hydrochloric acid. Mix, 
and preserve in a stoppered bottle. Tests,—specific gravity 1-074 ; 6 fluid 
drachms require for neutralization 93-88 measures of the volumetric solution of 
soda. 
Acidum Nitrodiydrochloricum Dilutum. B.P. 1867. 
Nitric acid, 1-42.3 fluid ounces. 
Hydrochloric acid, 1*16.4 fluid ounces. 
Distilled water.25 fluid ounces. 
Mix the acids, and allow them to remain for twenty-four hours in a bottle, the 
mouth of which is partially closed, then add the water in successive portions, 
shaking the bottle after each addition, and preserve the mixture in a stoppered 
bottle. Characters and tests,—specific gravity, T074; 352-4 grains by weight 
(6 fluid drachms) require for neutralization 920 grain measures of the volume¬ 
tric solution of soda. 
The specific gravity of the acid, as prepared by the directions of the Phar¬ 
macopoeia of 1864, is 1 070, and 3524 grains require for neutralization 93-88 
grains of volumetric solution of soda of the standard ordered in that work. 
The acid keeps well in ordinary temperatures, and appears to have little ten¬ 
dency to change. 
The nitro-hydrochloric acid, mixed as directed in the Pharmacopoeia of 1867, 
yielded the following results :—The specific gravity of the two acids, on admix¬ 
ture, and, after cooling, was 1-277, but on standing for twenty-four hours as 
directed, was 1-268. On adding the quantity of water for the production of 
the dilute acid, the specific gravity was found to be but 1-063, and 352 4 grains, 
or 6 fluid drachms, required but 840 measures of volumetric solution of soda 
for neutralization. 
This experiment having been conducted with a view to determine the loss of 
hydrochloric acid consequent upon leaving the mixed acids for twenty-four 
hours, the operation was conducted so that on the mixture of the two acids in 
a loosely-stoppered bottle, the escaping chlorine should be collected under a bell- 
glass, and should be received into a solution of potassa. This solution, at the 
end of the twenty-four hours, was subjected to estimation by means of nitrate 
of silver, and was found to be charged with chlorine, which, calculated as hy¬ 
drochloric acid, was found to be in such a proportion as to have diminished the 
strength of the nitro-hydrochloric acid by about 3 per cent. The loss of nitric 
acid was not estimated. 
