20 6 Sir Humphry Davy’s experiments on a solid 
do not think there can be any considerable error in the 
results. I give those which I consider as the most accurate. 
In one experiment, 3 grains of the substance afforded a 
quant' f y of oxygene equal to 517.3 grain measures of water, 
and lost in weight .68. In a second experiment, 2 grains 
afforded 348.3 grain measures of oxygene. In a third expe- 
riment, 1 grain yielded 191 grain measures of oxygene. 
Many experiments that I have lately made, have convinced 
me, that in my first paper I rated the number representing 
the proportion in which iodine combines too low ; indeed at 
the time, I stated that my results afforded rude approxi- 
mations, they demonstrated riferely that iodine was repre- 
sented by a very high number. In an experiment recently 
made with care, 50 grains of the iode of potassium decom- 
posed by nitric acid, afforded 32.8 grains of nitre. Accord- 
ing to this result, the number representing the proportion in 
which iodine combines is 227.3 5 hut I do not venture to state 
this number as exact, as I am not secure of the purity of the 
hydrate of potassa from which the iode was made. 
The compound of iodine and oxygene is very soluble in 
water ; it slowly deliquesces in a moist atmosphere, but re- 
mains unaltered when the air is dry; its solution first reddens, 
and then destroys vegetable blues, and reduces other vege- 
table colours to a dull yellow. When its aqueous solution is 
heated, as the water rises in vapour, it gradually thickens, 
gains the consistence of a syrup, becomes pasty, and at length 
by a stronger heat yields the solid substance unaltered ; unless 
a sufficient heat is applied to decompose a portion of it, when 
it gains a purplish tint apparently from some iodine set free. 
The pasty substance that it forms is evidently an hydrate, for 
it yields moisture during its decomposition. 
