New London Pharmacopeia. 351 
Benzoic Acid is an article which might very well be struck out of 
the Pharmacopeia ; the process, however, now directed is preferable 
to that of the last edition. 
A process for obtaining Citric Acid is given in this division, but it 
also has a place among the articles of the Materia Medica, and is so 
rarely prepared except by the manufacturer upon an extended scale, 
that the directions here given might well have been dispensed with. 
Mr. Phillips tells us that an ounce of water at 60° dissolves 10 
drachms of crystallized citric acid ; and such solution saturates about 
20 drachms of crystallized carbonate of soda. Nine drachms and a 
half of citric acid dissolved in a pint of distilled water, give, he says, 
asolution equal in strength to lemon juice. 
Weshall quote the article “* Muriatic acid” entire, that our readers 
may judge of the method which the translator pursues in his remarks 
and of their general usefulness to students and practitioners, 
Muriatic Acid. 
“ Take of dried muriate of soda, two pounds, 
Sulphuric acid by weight, twenty ounces, 
Distilled water, a pint and a half; 
*¢ First mix the acid with half a pint of the water in a glass retort, and 
to these, when cold, add the muriate of soda; pour the remainder 
of the water into a receiver; then, adapting the retort to it, let the 
muriatic acid distil into the water from a sand-bath, the heat being 
gradually raised until the retort becomes red hot. 
“The specific gravity of muriatic acid is to that of distilled water 
as 1-160 to 1°000. 
“One hundred and twenty-four grains of crystallized subcarbonate 
of soda, are saturated by 100 grains of this acid. 
** Process.—The nature of common salt, and the production of mu- 
riatic acid, are explained by two theories, both of which I shall state, 
because, from the name of muriate of soda which the college retain 
for common salt, it would appear that, as a body, they have not 
adopted the generally-received doctrines of Sir H. Davy on these 
subjects. 
«© On the supposition that muriatic acid is an undecomposed body, 
the explanation of its production is the following: Common salt, or 
muriate of soda, is a compound of muriatic acid and soda, and when 
it is mixed with the sulphuric acid, this, owing to its greater affinity 
for soda, expels the muriatic acid from it, which, being gaseous, and 
having considerable affinity for water, rises in the state of vapour 
with it, and is condensed in the receiver into liquid muriatic acid. 
The sulphuric acid and soda remain in the retort in the state of sul- 
phate of soda, 
** This process will be explained by the annexed diagram: 
i 
