106 
COMMERCIAL 
HYDROCHLORIC 
ACID. 
Oil of Hyosciamus and Oil of St. John's Wort. 
These are preparations frequently called for in this country, 
and are made by decoction. The first, by boiling one part of 
henbane leaves with four parts of olive oil, and allowing it to 
macerate several hours before straining. It is of a green co- 
lor, and used for frictions to calm pain. The latter Ms made 
in the same way, with one part of the summits of hypericum, 
and two parts of olive oil. It is of a fine red color, and used 
for sprains and bruises. 
ART. XXIV. — SELECTIONS FROM LASSAIGNE'S DICTION- 
NAIRE DES REACTIFS. — No. 2. 
Translated by Augustine Duhamel. 
Commercial Hydrochloric Acid. 
This acid, which is manufactured on a large scale, is com- 
monly colored yellow, as met with in commerce. This is 
owing either to a small quantity of decomposed organic mat- 
ter, or to a certain quantity of perchloride of iron, formed by 
the action of the hydrochloric acid upon the peroxide of iron 
existing in the vessels of stone in which it has been prepared. 
Independently of these two foreign substances, this acid is 
sometimes found to contain, in solution, chloride of lead and 
sulphurous acid: the presence of perchloride of iron may be 
shown in this acid by diluting it largely with water, and add- 
ing a few drops of a solution of ferrocyanate of potash: a 
deep blue color is immediately produced, and a precipitate 
shortly after. 
The existence of protochloride of lead is indicated by an 
examination of the residue of the evaporation or distillation 
of a portion of this acid. This compound is exhibited in the 
form of small scales, white, and pearl-like, sparingly soluble 
in cold, but soluble in boiling water. 
