IOWA ACADEMY OF SCIENCES. 
187 
silver salt was in excess, showing that in these cases satu- 
ration was not obtained, and that the bromide and iodide 
did not unite with sodium thiosulphate in these experi- 
ments, in the proportion corresponding to the equations of 
Cohen. 
In attempting to determine the solubility of silver iodate 
in sodium thiosulphate solution it was found that with 
strong thiosulphate solution and an excess of AgI0 3 a 
rather violent reaction occurred and much heat was 
evolved. It was found necessary then, to use a more 
dilute thiosulphate solution, so a N/ 10 solution was em- 
ployed. By shaking this with a small excess of AgI0 3 un- 
til the first signs of reaction appeared, requiring 20 to 30 
minutes, then by filtering off and weighing a portion of 
the solution and determining the silver an approximation 
at the amount of AgI0 3 dissolved was obtained. 
lOOc.c. n/10 thio. dis- 
solved AglOg GRAMS. 
GRAMS AglOg PER 
GRAMS THIO. 
4.26 
4 . 97 . 
1.176 
2.002 
Upon the molecular basis of iodide and iodate the 
AgI0 3 is about 16 times as soluble as the Agl. 
The reaction just described between the AgI0 3 and 
Na 2 S 2 0 3 has not, so far as known to me, been described 
in the literature, and the nearest approach to it is that 
described by Landholdt* on the action of sulphur dioxide 
on iodic acid. 
A preliminary experiment showed that with 1.5 mole- 
cules of thiosulphate to one molecule AgI0 3 there was no 
very apparent reaction, but when molecule for molecule 
was used practically all the AgI0 3 went into solution, that 
which remained blackened showing the formation of Ag s S r 
then began the precipitation of Agl which continued until 
there was no more silver in solution. It was deemed best 
to study the |reaction when the substances were put to- 
gether in equal molecules. After shaking and allowing to 
stand for about forty-eight hours the solution was found 
to be acid, neither silver nor thiosulphate was found in the 
* Berichte 19: 1317. 
