238 Proceedings of Royctl Society of Edinburgh. [sess. 
dissolved, but minute brown flocks remained behind, and these 
were proved to have properties identical with those of the 
“ hypoiodite.” 
When the “ hypoiodite ” precipitated from aqueous solution was 
heated at gradually increasing temperatures, the violet vapour of 
iodine was first observed at 130°, but even at 230° the decomposi- 
tion was by no means rapid. A quantity of the substance was 
introduced into one limb of a glass tube bent at right angles, the 
tube being then exhausted and sealed off. The empty limb was 
kept in cold water while the charged limb was heated in an oil-bath. 
After prolonged heating at 230°, very little iodine had condensed 
in the cool part of the tube, although the violet vapour could be 
distinctly seen. In the vapour of boiling anthracene (about 350°) 
the iodine still came off very slowly, and even after many hours’ 
heating the residue remained almost as deeply coloured as at first. 
A quantitative experiment resulted as follows. An amount of 
“hypoiodite,” which when dissolved in acid reacted with 9'5 c.c. 
of decinormal sodium thiosulphate, after twelve hours’ heating in 
anthracene vapour required 1*65 c.c. of the same solution to destroy 
the iodine liberated on dissolving the residue in hydrochloric acid. 
Thus 17 per cent, of the original quantity of iodine remained in the 
magnesia, the other portion having condensed in the cool parts of 
the tube. At a red heat iodine was given off rapidly and magnesia 
remained behind. 
Yapour-stained magnesia was still deeply coloured after exposure 
to a current of carbonic acid for several hours. 
Liquids in which iodine is soluble extract iodine from the 
“ hypoiodite ” only very slowly. Thus a quantity of “ hypoiodite ” 
corresponding to 11*4 c.c. of decinormal thiosulphate was treated in 
a Soxhlet apparatus for twenty-four hours with carbon tetrachloride 
(b.p. 75°). At the end of that time the residue was dark brown 
and required 6*0 c.c. of thiosulphate to destroy the iodine liberated 
on acidification. Accordingly, less than half the iodine had been 
removed by the prolonged extraction. A specimen, which had been 
prepared in chloroform solution with ignited magnesia, was similarly 
treated with chloroform in a Soxhlet extractor. After thirty hours 
it was still coloured, and still yielded iodine, although in very small 
quantity, when treated with a fresh portion of the solvent. 
