402 
PHARMACEUTICAL MEETING. 
chloride of iron escapes with the steam, and the resulting solution is weakened 
to a corresponding extent. In short, the process is practically a failure as a 
method of preparing a pure solution of perchloride of iron. If the presence of 
free hydrochloric acid in the solution is of no consequence, then the process is 
as good as any other ; in that case it is only necessary to add, say, one-fourth to 
one-sixth more hydrochloric acid than is necessary for the reaction ; the black 
compound is then easily decomposed, so also is any nitrate of iron that may have 
been formed ; excess of nitric acid is also got rid of, and, excepting the presence 
of free hydrochloric acid, the solution is all that could be wished. Such a solu¬ 
tion must, of course, be termed “ acid solution of perchloride of iron,” and its 
acidity will be variable in amount. It would surely be better that the officinal 
solution should be pure ; prescribers could then order the addition of any quan¬ 
tity of acid they might desire or have no free acid present,—an alternative that 
could not be enjoyed if this or any other faulty process for the preparation of 
solution of perchloride of iron were permanently adopted. 
Liquor Ferri Perchloridi , B. P .—Before leaving this, the third of the pro¬ 
cesses that I have alluded to for the preparation of perchloride of iron, it will be 
as well to notice the adaptation of it given in the British Pharmacopoeia. To 
2 ounces of annealed iron wire, or binding wire, a mixture of 10 fluid ounces of 
aqueous hydrochloric acid (of sp. gr. 1T7) and 5 fluid ounces of water is to be 
added in successive portions, the resulting evolution of hydrogen gas being 
assisted by the application of “a gentle heat.” Assuming that the words “ a 
gentle heat ” have their usual meaning, namely, a temperature entirely at the 
discretion of the operator, and disregarding the injunction to add the diluted 
acid “in successive portions,” the metal is simply placed in the liquid, and the 
whole set aside anywhere in the summer time, or in a warm place (say at a tem¬ 
perature of 80° to 100° F.) in the winter, until the whole of the iron is dissolved. 
The operation will generally occupy less than a day. The solution must now be 
filtered, to separate the carbon set free from the iron wire ; it is small in quan¬ 
tity by weight, but rather bulky, and if not removed would give the final pro¬ 
duct a dark-coloured appearance. By the w T ay, the direction to filter has been 
omitted from the Pharmacopoeia description of the process. A mixture of 6 fluid 
drachms of nitric acid (of sp. gr. 1*5), diluted with 2 fluid ounces of water, is then 
added to the solution of iron, and the Avhole reduced by evaporation from its bulk 
of about 18 fluid ounces to 10 fluid ounces. Now, contrary to what has been 
stated by several operators, this method of working has yielded in my hands a 
clear, stable solution of the proper rich brown colour, and containing no proto¬ 
salt. I can only suppose that others have used weak acids or have applied too 
much heat in the first stage of the process, and thus lost acid. But, as I stated 
in the lectures which I had the pleasure of delivering before the members of the 
Pharmaceutical Society in the early part of last year, the resulting solution con¬ 
tains pernitrate of iron. Moreover, it is deficient in acid ; hydrochloric acid has 
been lost from some of the hydrated perchloride of iron during evaporation, and 
though the peroxide of iron formed may not be in sufficient amount to remain as 
a permanent precipitate, but is dissolved in the residual perchloride of iron, the 
solution, from the absence of free acid, soon reacts on the spirit of wine it may 
be mixed with to form the so-called tincture, and a solid basic compound of per¬ 
chloride of iron separates, and, from its lightness, remains suspended in the 
liquid; in short, the tincture is spoiled. With regard to the pernitrate of iron, 
its presence is due to the employment of more nitric acid than is necessary. 
Theoretically, 2 ounces of iron, or 875 grains, require 1711 grains of anhydrous 
hydrochloric acid and 281 grains of anhydrous nitric acid (NO s ). 1711 grains 
of anhydrous hydrochloric acid are contained in 9 fluid ounces and 6 fluid 
drachms of aqueous hydrochloric acid of sp. gr. 1T7 ; and 281 grains of the body 
N0 5 are contained in 4 fluid drachms and 18 minims of aqueous nitric acid of 
