114 
ORIGINAL COMMUNICATIONS. 
The last process which I shall notice is that described by Tur- 
ner, in the fifth edition of his chemistry, and is as follows: "add 
iodine to a hot solution of potassa until the alkali is neutralized, 
when iodide of potassium and iodate of potassa will be gene- 
rated; evaporate to dryness, and expose the dry mass in a 
platinum crucible to a gentle red heat, in order to decompose 
the iodate. Then dissolve out the fused mass by water and 
crystallize." , - 
The rationale of the action of iodine on potassa has already 
been given, on the supposition that the iodide of potassium 
becomes hydriodate of potassa by solution. If, however, it 
is supposed that the iodide of potassium exists as such in so- 
lution, the rationale will be somewhat different and may be 
explained as follows: — Five atoms of iodine unite with five of 
potassium, forming five atoms of iodide of potassium, while 
the five atoms of oxygen derived from the potassa, unite with 
one of iodine, forming one atom of iodic acid, which unites 
with an atom of potassa, forming iodate of potassa. The pro- 
portion of the iodide to the iodate, according to these views, 
is as 1423 to 5515 or as 1 to 3^, nearly. 
Berzelius recommends that the iodate of potassa be sepa- 
rated from the solution by crystallization, and that the mo- 
ther water containing the iodide, be evaporated to dryness 
and fused, as before. The separation of the iodate is intended 
to prevent the mass from bubbling up and throwing portions 
of it out of the crucible. 
Of the different processes noticed, this last appears to be 
decidedly the best, being the most simple and easy of execu- 
tion. 
It has been said, that " iodide of potassium is partially 
decomposed by sulphuric ether. In digesting iodide of potas- 
sium, in this menstruum, it becomes highly coloured with a 
portion of iodine, which separates from the salt; the iodine 
attaches itself to the sides of the vessel, at the surface of the 
liquid; what remains after pouring off* this liquid, appears to 
be a subiodide of potassium." I have repeated this experi- 
ment without obtaining any indications of the decomposition 
of the iodide. 
