224 COMPOUND OP IODIDE OP SODIUM AND IODATE OF SODA. 
little solution of sulphate of soda was very easily removed. 
When it is desired to employ chlorine in place of nitric acid 
as the bleaching agent, the same process may be adopted. 
Ibid. 
ART. XLVIL — COMPOUND OF IODIDE OF SODIUM AND 
IODATE OF SODA. 
Prop. Fred. Penny, in the Transactions of the British As- 
sociation, for 1840, describes a compound of iodine and soda, 
which appears to be the sesqui-sodii-iodide of iodate of soda. 
When examining the action of iodine on carbonate of soda, 
he obtained a salt which crystallized in regular six-sided 
prisms, which was white, inodorous, of a sharp saline taste? 
neutral to test paper, readily soluble in hot and cold water, 
but decomposed by alcohol into iodate of soda and iodide of 
sodium. Its solution gives a lemon-yellow precipitate with 
acetate of lead, yellowish white with nitrate of silver, and 
fine bright yellow with pernitrate of mercury. It is not af- 
fected by solution of starch, but instantly decomposed with 
precipitation of iodine by the stronger acids. It may also be 
obtained by the action of iodine on caustic soda. When the 
solution was evaporated spontaneously, Professor Penny 
found that long prismatic crystals of iodate of soda were de- 
posited ; but as the evaporation continued, these crystals 
were re-dissolved, and replaced by those of the double salt. 
The prior deposition of the iodate of soda, generally occurs 
in the preparation of this salt, and it appears necessary that 
there should be an excess of iodide of sodium present in the 
solution, and that the solution should be strong, in order that 
the salt should form. When this salt is dissolved in water, 
and the solution evaporated spontaneously, crystals of iodate 
of soda deposit, but very few of the double salt will form 
