ON THE HYDRARGYRO-BINIODIDES OP POTASSIUM, ETC. 273 
It appears to require the presence of free ammonia for its pre- 
servation. In order to ascertain, approximately, its composi- 
tion, a portion of it, as free from uncombined ammonia as pos- 
sible, was put into water and shaken, by which it was decom- 
posed, ammonia being dissolved, and biniodide of mercury 
subsiding. The latter was dried and weighed, and the am- 
monia contained in the water carefully neutralized with crys- 
tallized tartaric acid. The Hgl 2 weighed 6.0 parts. The li- 
quor required 2.0 parts (t + HO) for saturation, which, by 
calculation, indicates .454 parts ammonia, that is 
6.000 parts Hgl 2 C corresponding £ 1 atom Hgl 2 454.6 
.454 " NH 3 i nearly with 5 2 " NH 3 34.30 
After the above had been prepared, my attention was directed 
by one of the editors of this Journal, to Professor Kane's re- 
searches respecting the ammoniacal chloride of mercury; from 
the similarity of the mode of formation of this compound, it 
seemed probable that its composition might also be similar, 
and in order to ascertain whether this was the case, some fur- 
ther experiments were made. 
When to a solution of 2 atoms of bichloride of mercury, 4 
atoms of ammonia are added, the whole of the mercurial salt 
is precipitated, and 2 atoms of hydrochlorate of ammonia re- 
main in solution. According to Professor Kane's views, the 
chlorine of the hydrochlorate of ammonia is furnished by the 
decomposition of 1 atom of the bichloride, the hydrogen by 
the decomposition of 2 atoms of ammonia, leaving amidogen, 
(a hypothetical compound of 1 atom of nitrogen and 2 atoms 
of hydrogen,) 2 atoms of which combine with 1 atom of mer- 
cury, forming the bi-amidet of mercury, which unites with the 
remaining atom of bichloride of mercury to form white pre- 
cipitate, (HgCl 2 -f Hg2NH 2 .) Accordingly, Professor Kane 
found when white precipitate was decomposed by heat, 2 
atoms chloride of mercury remained, and the ammonia and 
nitrogen which were driven off, were in the proportion to form 
2 atoms of amidogen. 
With a view to ascertain whether similar phenomena were 
VOL. VI. — NO. iv. 35 
