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SELECTED ARTICLES. 
with water. On being exposed to the action of heat, this sub- 
stance swells and is reduced to a very light porous charcoal. 
We do not venture to assert that this substance is a per- 
fectly pure immediate principle, but from what has been said, 
it will be perceived that it is analogous to the saponine of M. 
Bussy, from which, however, it differs in some essential par- 
ticulars. 
Bull. gen. de Therap. 
ART. XLI. — RE MARKS ON THE NOTE BY M. BOUTIGNY, 
ON THE PREPARATION OF PROTOIOD1DE OF MERCU- 
RY. By M. Berthemot. 
Some years since, I paid particular attention to the iodides 
of mercury, and pointed out the difficulty of obtaining the 
protoiodide in a pure state, by double decomposition. I 
therefore proposed the direct combination of iodine and mer- 
cury, in exact proportions. Experience has confirmed my 
views. The value of this method was soon admitted, and 
MM. Orfila and Soubeiran adopted it as the best, as did also 
M. Dumas who has cited it in his work on chemistry as 
always affording a pure product. 
What I said on this preparation in the Journal de Phar- 
macie (see Journ. Phil. Coll. Pharm. iii. 353,) would require 
nothing in addition if I had not met with a note on the sub- 
ject by M. Boutigny in which this pharmaceutist, whilst ad- 
mitting that my method is the simplest and most direct, 
asserts that it is defective, and advises its rejection as affording 
an indefinite product, &c. This assertion appears to me to be 
erroneous, and I will therefore examine the subject in detail, 
and thus overthrow his objections. 
The formula I indicated is 
1 atom mercury 1.265.822 } Mercury 61.60 per cent. 
1 iodine 789.145 $ Iodine 38.40 
2.054.967 
100.00 
