HYDRATED PEROXIDE OF IRON. 
37 
ting the above mentioned process in practice, and furnished 
the oxide to the patients in twenty minutes after being adver- 
tised of the demand. 
In conclusion we may observe, 
1st. That hydrated peroxide of iron, even when kept under 
water, gradually decreases in its power of neutralizing arse- 
nious acid. 
2d. That if kept in the form of a thick magma, it will re- 
tain its properties longer than when mixed with much water. 
3d. That this decrease in power is probably due to a change 
in the relative proportion of the oxide, and the water chemi- 
cally combined with it, as well as to an alteration in its state 
of aggregation, 
4th. That from the experiments of Orfila, and others, the 
dry hydrated oxide possesses the power to a considerable ex- 
tent of neutralizing arsenious acid, and it should be used in 
the absence of the moist and recent preparation. 
5th. That hydrated peroxide of iron may be obtained in a 
state fit for use in 10 or 15 minutes, by using a solution of the 
persulphate of iron. And, 
Lastly. That the recent oxide should be used In all cases 
where it is attainable, in preference to that long kept. 
REPORT. 
The Committee to" whom was referred the " Observations 
on Hydrated Peroxide of Iron," &c. by Wm. Procter, Jr., 
respectfully 
Report, That they have little to add to the full remarks 
upon this subject contained in the paper referred to them. 
With regard to the change in the state of aggregation, induced 
by keeping the hydrated peroxide suspended in water, their 
own observations have confirmed those of Mr. Procter, and 
they consider his experiments as conclusively showing that 
we cannot rely upon the hydrated oxide after it has been pre- 
pared a certain length of time. 
