1896 - 97 .] On the so-ccdlecl “Hypoiodite of Magnesium .” 239 
Water does not dissolve out free iodine from the “ hypoiodite ” 
either at the ordinary temperature or at the boiling-point. This is 
probably due to the slight solubility of iodine in water, enough 
magnesia being simultaneously dissolved to convert the iodine into 
iodide and iodate. The filtered aqueous solution at once gives free 
iodine on acidification. A small quantity of the “hypoiodite” 
left in water at the ordinary temperature becomes decolorised after 
several days, or disappears entirely. In boiling water it loses its 
■colour in a few minutes. 
An aqueous solution of potassium iodide extracts iodine from the 
“ hypoiodite ” at the ordinary temperature. If the liquid is de- 
canted off and the precipitate treated with successive fresh portions 
of the iodide solution, iodine continues to he extracted in gradually 
diminishing quantity until the residue is colourless. In the last 
extracts there is no free iodine, but iodine is liberated from them 
on acidification. 
Quantitative Experiments. 
In order to ascertain if the “ hypoiodite ” were a real chemical 
compound or not it was necessary for us to perform quantitative 
experiments, as a study of the qualitative behaviour of the body 
alone could lead to no definite conclusions. We wished in par- 
ticular to determine if the substance were not analogous to the so- 
called iodide of starch, which has recently been shown by Krister 
{Liebicfs Annalen , 1894, 283, 360) to be no true chemical com- 
pound in the ordinary sense, but a substance of composition varying 
with the strength of the iodine solution used in its preparation. 
A preliminary set of experiments was made by shaking up 
magnesia with decinormal solution of iodine in aqueous potassium 
iodide for varying times, in order to determine the approximate 
amount of iodine absorbed, and that converted into iodide and 
iodate under these conditions. After shaking for a definite time 
the brown solid was filtered off, drained, and washed free from ad- 
hering solution with a little water. So long as calcined magnesia 
was employed, no difficulty was experienced in filtering and washing 
the precipitate, but when the magnesia was formed in the solution, 
as was the case in the majority of the later experiments, the pre- 
cipitate was rather unmanageable. A Gooch crucible with a fine 
