HYDRATED PEROXIDE OP IRON 
29 
ART. IV. — OBSERVATIONS ON HYDRATED PEROXIDE OF 
IRON, DEMONSTRATIVE OF ITS DECREASE IN POWER, 
AS AN ANTIDOTE FOR ARSENIOUS ACID, BY AGE, AND 
SOME HINTS ON THE METHOD OF PREPARING IT. By 
Willam Procter, Jr. 
Read at the Pharmaceutical Meeting of the College, Feb. 28th, 1842. 
Few subjects have attracted more attention in the medico - 
chemical world, than that of the antidotal power of the hy- 
drated peroxide of iron, in its relations with arsenious acid ; 
and indeed so many papers have been already written upon it, 
that nothing but the importance of some of the views now 
offered, would have induced the writer to have added to the 
number. 
Many months ago, in preparing some tartrate of iron and 
potassa, not having quite enough of the recently precipitated 
oxide of iron, a portion of the hydrated oxide, which had 
been prepared nearly a year before as an antidote, and kept 
under water, was resorted to, but it was observed that the 
latter was dissolved very slowly by the tartaric acid, and the 
great difference in that respect from the recent, was a matter 
of surprise, and suggested the idea that a like difficulty would 
occur in a still greater degree, when arsenious acid was em- 
ployed. 
Under the impression that, if several specimens of the hy- 
drated peroxide of different ages; which had been kept under 
water, were subjected to trial, as to their activity in removing 
arsenic from solution, conclusions might be drawn which 
would settle the question definitely, a series of experiments 
were undertaken, and the result of these corroborate the sug- 
gestion, that this substance gradually decreases in activity by 
age, notwithstanding it may be kept under a stratum of wa- 
ter. If this position is fairly established, as it is believed to 
