ON THE ACTION OF SAL AMMONIAC, ETC 197 
mixture enclosed in a linen bag, may be successfully used 
for a long time in chronic complaints, in which the slow and 
constant disengagement of iodine is applicable. At the end 
of six months, there was no traces of iodide of potassium in 
the mixture, and the residue consisted of sal ammoniac, and 
chloride of potassium. 
Iodide of potassium is decomposed by sal ammoniac at an 
elevated temperature. When a mixture of these two salts is 
heated in a retort, by the flame of a spirit lamp, there pass- 
ed into the receiver, besides sal ammoniac, iodine of the iodide 
of potassium; the whole of the iodide is not, under these cir- 
cumstances, decomposed by the sal ammoniac. When the 
whole of the sal ammoniac is volatilized by a red heat, the 
residue contains, besides chloride of potassium, a little iodide 
of potassium. 
•fiction of Ether on the Iodide of Potassium, and on the 
Iodide of Lead. 
Well formed crystals of iodide of potassium very slightly 
attract moisture from the air, but undergo no other change ; 
also a solution of this salt is not decomposed by contact with 
the air. On the contrary, when we moisten the crystals, well 
dried and powdered, with ether, they assume after sometime 
a yellow color, and contain free iodine. I have boiled this 
salt four or five times in successive portions of ether, and 
each time iodine was dissolved ; the residue thus treated had 
become slightly alkaline, but still contained much iodine. 
This partial decomposition, by means of ether, also takes 
place with compounds of iodine, which are with difficulty 
dissolved in water. 
When for example we digest the yellow plates of iodide of 
lead in ether, this liquid becomes of an orange yellow and 
contains iodine, but no lead. By repeated actions we come 
to a point at which the ether is no longer colored, and does 
not dissolve any more iodine. The residue upon which the 
ether no longer acts, has lost the brilliant gold color which it 
previously had, and become brownish yellow, with no lustre. 
