ON THE HYDRARGYRO-BIN IODIDES OF POTASSIUM, ETC. 267 
had been recently precipitated — to a hot solution of KI, HgCl 2 
was added; the HgP resulting was first precipitated, and 
then re-dissolved in the liquor. By this means, in a solution 
of 
165 parts KI, 
90 " HgCl 2 
were dissolved. This was as much as could be taken up, as when 
more HgCl 2 was added, it remained unacted upon. It is in 
the proportion of three atoms KI to one atom HgCl 2 ; as two 
atoms KI are decomposed by reaction with one atom HgCl 2 
forming one atom Hgl 2 and two atoms KC1, the solution con- 
tained 
1 atom Hgl 2 
1 « KI, 
together with two atoms KC1. 
The double salt, therefore, containing the highest propor- 
tion of Hgl 2 , which I have been able to obtain, consists of 
HgI 2 +KI. 
2d. On allowing the hot solution containing 385 parts Hgl 2 , 
and 165 parts KI, to cool, 165 parts Hgl 2 crystallized from it. 
The clear liquor was poured off from the free Hgl 2 , and con- 
centrated by evaporation; on cooling, the double iodide was 
obtained in long, yellow, flattened prisms, resembling crys- 
tallized sulphur. These crystals, by synthesis, are composed 
of 220 parts Hgl 2 , and 165 parts KI. They were analysed by 
heating them in a tube closed at one end, first, gradually to 
drive off the water of crystallization, and then, with a stronger 
and carefully regulated heat, in order to sublime the Hgl 2 , 
taking care that it should all condense in the upper portion of 
the tube. When all the biniodide had sublimed, the tube was 
divided between it and the KI, which remained at the bottom, 
and the products were carefully weighed. 100 parts of these 
) crystals, by a mean of several analyses thus conducted, are 
composed of 
