248 
SELECTED ARTICLES. 
manipulation, and yet it was found in the product in the same 
state as at the moment of formation. 
Honey has here an indisputable advantage over sugar; in 
the first place, it more certainly prevents oxidation, — besides, 
as it never takes on the solid form, it more completely en- 
velopes the ferruginous matter, and preserves it throughout 
from the influence of oxygen. The carbonate itself, in the 
midst of this humid mass, does not cohere, but remains highly 
soluble in acid liquids. 
We shall now report, in detail, both the method of M. 
BonsdorfT for the sulphate of iron, and that of M. Vallet for 
the preparation of the ferruginous pills. 
To prepare the sulphate of iron by the method of BonsdorfT, 
commence by dissolving pure iron filings in pure diluted 
sulphuric acid, by the aid of moderate heat; this mixture is 
poured into a glass matrass with a long neck and an opening 
of small diameter, in order to avoid, as much as possible, the 
entrance of air; a little iron filings in excess is added, and the 
solution is boiled until it will no longer dissolve the iron, 
which is determined by the liquid assuming a peculiar deep 
brownish gray color. When the solution is sufficiently con- 
centrated to be disposed to crystallize, it begins to foam, and 
it is requisite to manage the heat with great caution. To 
filter the liquid, a funnel is selected with a beak as narrow as 
possible; and, when the filter is moistened with water, the 
solution is poured into it, and received into a glass capsule 
previously moistened with a little sulphuric acid. In fact, 
this small excess of sulphuric acid entirely prevents the still 
further oxidation of the iron, and the filtered solution remains 
perfectly clear; while, on the contrary, without the addition 
of the acid, itimmediately becomes turbid, or deposits pellicles, 
and soon after, a precipitate of hydrated oxide, — which, as is 
well known, assumes a color at first of a grayish green and 
afterwards a yellowish brown, (by forming a basic salt.) It 
is also necessary, in consequence of the turbidness, to bring 
down the beak of the funnel to the bottom of the vessel, 
because, however little the distance between them, the 
