19S 
ON THE ACTON OF SAL AMMONIAC, ETC. 
Boiling water now dissolves scarcely a trace of the iodide, and 
does not become colored. On heating this residue with the 
contact of air, and treating it with nitric acid, it reacts like 
pure oxide of lead, but still contains iodine which cannot be 
separated by the ether. 
Aldehyd does exert similar decomposing action upon 
the crystallized iodide, but under these circumstances much 
ether is eliminated. 
The action of other Chlorides upon the Iodide of Potassium. 
No other chloride besides sal ammoniac appears to have 
the property of decomposing iodide of potassium, at ordinary 
temperatures, and in contact with the air. Iodide mixed with 
chloride of potassium, undergoes no change by exposure to 
the air for eight days ; no iodine is set free. 
A mixture of iodide of potassium and chloride of sodium, 
disengages, at the end of some days, a trace of iodine, but it 
appears to me that this decomposition is not due to the chlo- 
ride, but to some foreign admixture. As sea-salt coming 
from all the manufactories of Bavaria, contains traces of sal 
ammoniac, I sublimed the sal ammoniac by means of a dull 
red heat, and when cool, mixed the salt with iodide of potas- 
sium. This 'mixture, left exposed on a stand for eight days, 
did not disengage any iodine, but a similar mixture spread 
upon paper colored it of a very bright yellow, after some 
days, and the paper contained traces of iodine. The iodide of 
potassium is decomposed, however, in a very marked manner 
at a high temperature, when mixed with chloride of sodium, 
or even with chloride of barium, and heated by the flame of 
alcohol in a glass retort. 
Sal ammoniac, therefore, appears to be the only chloride 
which can produce a slow decomposition, at ordinary tem- 
perature and in contact with a moist atmosphere. 
We may add, likewise, that sal ammoniac always slightly 
reddens^tincture of litmus, and may act up to a certain point, 
as an acid salt, which would decompose the iodate of potassa, 
when a small quantity of this salt exists in 'the iodide. But 
