ON DIAPHORETIC ANTIMONY. 
301 
nitrate of potassa, three parts, as directed by the Brunswick 
Dispensatory; the materials are reduced to powder, they are 
mixed exactly, and thrown by portions into a crucible, pre- 
viously heated to redness. The matter is maintained at a red 
heat, during an hour and a half when cold; the product is 
thrown into four parts of water, decanted, and the liquid 
placed aside. The residue is three times to be boiled with 
the same quantity of water; the liquids are mixed, and the 
washing is finished by boiling water, which only removes the 
slightest traces of antimoniate. The product thus washed, is 
impure bi-antimoniate, but free from hypo-antimonite. If 
through the washing liquids a current of carbonic acid gas be 
passed, a very abundant precipitate is obtained, which is pure 
bi-antimoniate. As the carbonic acid can only separate a part 
of the potassa, the precipitate is necessarily formed of bi-anti- 
moniate. 
M. Berzelius remarks, that in the preparation of diaphoretic 
antimony, if the calcination be prolonged, the hypo-antimo- 
nite and the antimonite of potassa, are transformed into a neu- 
tral soluble antimoniate: the waters of washing, then, which 
are obtained, ought to furnish the greatest possible quantity of 
precipitate; which is the same as saying, that if we wish to 
employ the product of which we have spoken, it is necessary 
to prolong the calcination as much as possible, (during an hour 
and a half, or nearly,) to reject the insoluble product, after it 
has been well washed, and to preserve only the precipitate by 
the waters of washing, furnished by carbonic acid. The 
reiterated experiments which we have made upon this subject, 
have proved to us that, by this means, we can obtain more 
than three-fourths of the mixture employed. 
If now we consider that heretofore the washings were re- 
jected as valueless, it can be admitted that our method, inde- 
pendently of the goodness of the product, furnishes also a large 
enough quantity. 
The antimoniate thus obtained is of perfect whiteness. We 
have analysed it by heating it to a red heat in a platina cruci- 
ble, then by calcining another part in a tube, and receiving 
