ON HYDRATED PEROXIDE OP IRON, ETC. 245 
12. Mr. Deville, of Paris, successful. Jlmer. Journ. Med. 
Set., May, 1839, p. 243. 
13. Dr. Puchelt, Jun., seven cases of recovery. Edinburgh 
Med. and Surg. Journ., vol. liv. p. 263. 
It would not be difficult to add considerably to this list. 
But I have adduced enough to warrant a belief in the 
efficacy of the antidote. I trust, however, that none of my 
readers will be led to suppose, that in cases of poisoning by 
arsenic, they are to depend solely on it. Vomiting should 
be promoted as early as possible, and indeed every mode 
now in use for the speedy evacuation of the poison. The 
antidote will find sufficient to operate on what still remains 
and cannot be removed. 
IV. The Mode of Preparation and Exhibition. Las- 
saigne had recommended the following process. Take iron 
turnings, pour on them four times their weight of the nitric 
acid of commerce gradually, so as to avoid too rapid an ac- 
tion. A portion of the nitric acid will yield its oxygen to the 
iron, and change it to a peroxide, which unites with the unde- 
composed nitric acid, and forms pernitrate of iron. As soon 
as the action of the nitrous vapor has ceased, add ten or twelve 
parts of water to dissolve the pernitrate and to precipitate the 
undissolved turnings. Decant and filter the solution, and add 
aqua ammonia, until litmus paper becomes blue. A yellowish 
brown precipitate is formed, which is the hydrate, and which 
should be washed with boiling water, to free it from the re- 
mains of the acid. 
Drs. Bunsenand Berthold, however, prefer that prepara- 
tion obtained by taking a pure solution of the sub-sulphate of 
iron, increasing its dose of oxygen by heating it with nitric 
acid, and then pouring into the solution an excess of caustic 
ammonia. The hydrated oxide is now obtained by decanta- 
tion. They advise that the nitric acid be added in small por- 
tions at a time, otherwise a quantity of the neutral sulphate of 
the sesquioxide is separated in the form of a yellow powder, 
which is but slightly soluble. They also insist on the danger 
of using any other alkali than ammonia. 
