ON THE AMMONIO-IODIDES OF MERCURY. 
91 
produces it, its formula appears to be Hgl 2 + 2Hg~fHgN 2 H 4 , 
(or HgP + 2Hg -f Hg2 NH 2 . ) 
The formula of the iodine compound, corresponding to 
white precipitate, should be HgI 2 + Hg2NH 2 , but it does not 
appear that this product can be obtained. 
M. Rammelsberg has also made some researches on the 
action of ammonia on the protiodide of mercury. He found 
that when this substance was digested in aqua ammonise, at the 
ordinary temperature, a black powder was formed, which was 
the ammoniacal protiodide. The evanescent nature of this 
compound, together with the facility with which the protio- 
dide itself is decomposed, renders it very difficult to analyse; 
by drying alone it loses all its ammonia. If the protio- 
dide is boiled with solution of ammonia, a black precipitate is 
produced which contains much metallic mercury, and the li- 
quor, on cooling, deposites white crystals of the ammonio- 
biniodide. 
