ON HYDRATED PEROXIDE OP IRON. 
5 
produced. Dr. Von Specz employs the powder in all his 
experiments with the hydrated oxide, which could not have 
been an immediate preparation, finds that it can be preserved 
a considerable time, and finally discovers that other peroxides 
may be used in default of the hydrate, one of which is as old 
as the creation, the other, age unknown. It is true the hy- 
drate is always to be preferred, but its place can be supplied. 
Dr. Robson also gave the hydrated oxide as soon as it could 
be got ready, (an hour and a half after the carbonate was 
given,) but his patient had been already relieved by the old pre- 
paration, first swallowed. The recent preparation was not well 
washed, and many urgent symptoms supervened upon its use. 
" He (the patient) said he felt sick, and worse after taking the 
physic." The next morning, the prepared oxide, more care- 
fully washed, was given. " It was not so good to take, but he 
had no more sickness," &c. 
These, then, it is asserted, prove that age is no obstacle to 
the effects of peroxide of iron; that it can be kept, and that 
the precipitated peroxide must be thoroughly washed. It can 
scarcely be necessary to remind the readers of a scientific 
journal that the carbonate of iron, and haematite, are almost 
wholly peroxide of iron. The former containing a trifling 
amount of carbonic acid; the latter, perhaps, some siliceous 
or earthy matter. My own view is, that these would be 
equally efficacious as antidotes, if in an equally impalpable 
state, with the precipitated peroxide. 
The only possible reason which I can conceive for requiring 
the oxide to be freshly prepared, is that it may be adminis- 
tered in as finely divided a condition, as nearly approaching 
solution as possible; and this certainly can only be accom- 
plished by employing it in the pulpy state of a recent preci- 
pitate. This state is, however, not inconsistent with age, and 
may always be preserved, for any reasonable length of time, as I 
know by experiment, simply by suffering enough of the water 
with which the precipitate has been washed, to remain, in order 
that the oxide may be diffused through it. So very minutely 
divided is the oxide in its precipitated state, that a trifling 
