ON NEW FERRUGINOUS PILLS. 
245 
Of iron and carbonate of potassa, which by double decomposi- 
tion affords sulphate of potassa and carbonate of iron. Such 
for instance as Griffith's pills, adopted by the London Phar- 
macopoeia, the emenagogue pills of the Spanish Pharmaco- 
poeia, and the pills prepared according to the more recent and 
better known formula of Dr. Blaud de Beaucaire. These for- 
mulae are rational, in despite of what has been said of them, by 
the author of the Pharmacopee Universelle who has not per- 
ceived that the chemical decomposition was foreseen and essen- 
tial to the nature of the medicine. M. Vallet assures us that, 
at the moment that they are made, these preparations contain 
sulphate of potassa, carbonate of potassa, and carbonate of iron, 
but that the last, although enveloped in a consistent mass, does 
not escape its habitual decomposition, as the oxygen of the at- 
mosphere converts it by little and little into an hydrated 
peroxide of iron. 
We have exposed to the air, the recently made pills of 
Blaud, forming a sheet three lines thick. At the end of three 
days, a dry and ochreous layer was formed upon its surface. 
The protoxide of iron had completely disappeared; the water 
separated it from the sulphate, carbonate, and bicarbonate of 
potassa; by means of the last named salt, there was held in 
solution a little of the protoxide and some traces of the per- 
oxide of iron; this metal was almost entirely converted into 
an hydrated peroxide. The lower layer, still soft, had not 
as yet undergone so decided an alteration. The carbonate of 
iron in this part was observed in considerable quantity, but 
the rust color of the mixture exhibited the advanced degree 
of oxidation it had undergone. There is wanting, then, 
to the formula of Dr. Blaud, as to that of which it is an imi- 
tation, the stability which is an essential character of a good 
medicine; it is not on the next day what it was the day pre- 
vious; its composition changes with the age of the prepara- 
tion. 
Griffith has proposed, under the denomination of a mixture, 
a preparation that differs from the preceding; in as much as 
the two salts are decomposed in an aqueous vehicle, the reac- 
vol. in. — no, iv. 32 
