252 
SELECTED ARTICLES. 
As soon as the water is added, there is, as has been stated, a 
formation of protoiodide of mercury, but as the decomposi- 
tion of the two salts is not immediately complete and as the 
undecomposed hydriodate exercises an action not only on the 
remaining protochloride, but also on the newly formed proto- 
iodide, this latter is partly changed into metallic mercury 
which mixes with the precipitate and partly into deutoiodide, 
which being dissolved in the water forms with the hydriodate 
in solution a compound salt of deutoiodide of mercury and 
iodide of potassium. As to the insoluble precipitate, it is 
formed of metallic mercury, protochloride of mercury and 
iodide of the same metal. This method therefore should not 
be followed, and even admitting that in the preparation of 
the protoiodide in this way that the decomposition was exact; 
the product would not differ from that produced by my plan. 
, i t C mercury, 24.69 
89 parts calomel, = } chlorin £ 4 31 
nr , , , . , . C potassium, 
20 parts hydriodate, = ,. 7 
r J ' £ iodine, 
29.00 
4.74 
15.26 
20.00 
Hence, 100 parts of an iodide of mercury obtained in the 
proportions of 15.26 iodine, and 24.69 mercury, would be 
composed of 
Per cent, mercury, 60.88 
iodine, 38.12 
100.00 
The following formula results from the direct combination 
of one atom of each: 
Mercury 61.60 
Iodine 38.40 100.00 
It is therefore evident that if the iodide could be obtained 
perfectly pure by the method of M. Berthemot, it would give 
the same results. 
Bull. gen. de Therap. 
