104 RESEARCHES ON THE AMMONIAC AL COMPOUNDS. 
of hydrogen to combine with four of nitrogen, to form am- 
monia, while the remainder of the nitrogen comes over in a 
free state. 
If the experiments to ascertain the amount of oxygen in the 
compound are satisfactory as to its non-existence, then the re- 
sult of the decomposition, effected by iodide of potassium, will 
afford additional evidence of the correctness of this formula ; 
for, while the iodine unites with the mercury to form the per- 
oxide, and the chlorine with part of the potassium, the decom- 
position of water becomes necessary to account for the con- 
version of the remainder into the free potassa which exists in 
the solution, and hence will be derived the hydrogen necessa- 
ry to form the ammonia from the arnidogen. 
The fact of the absence of oxygen from the compound, has 
been verified by M. Ullgren,* who has also substantiated the 
composition of white precipitate, as advanced by Prof. Kane. 
M. U. is satisfied that when this substance, perfectly dry, is 
heated gradually to fusion, and then treated with perfectly dry 
hydrochloric acid gas, no water is formed, but there results a 
liquid mixture of chloride of mercury and sal ammoniac. 
These considerations would seem clearly to point out the 
existence of nitrogen and hydrogen in this and analogous com- 
pounds, but there is yet another view which has been taken, 
in which part of the nitrogen is supposed to be directly com- 
bined with the metal, and the remainder to unite with the hy- 
drogen and constitute one of the elements of the compound 
under the form of ammonia, or that the amidets are nitrurets 
combined with ammonia. M. Mellon, who has advanced 
these views, considers that nitrogen, in ternary combination 
with a metal, plays the same part as oxygen, sulphur, &c, and 
forms azo-salts, as the others do oxy-salts, sulpho-salts, &c. 
This view will certainly explain the composition of these 
bodies, but with much less simplicity than the theory of the 
amidets. 
* Ann. der Pharm., t. 27. 
