ON A NEW COMPOUND, ETC. 
231 
was evaporated to dryness, by which the oil was partly vola- 
tilized and partly decomposed. Heat was now cautiously 
applied, so as to reduce the iodate, which I have already 
stated to be always formed in such experiment, to the state of 
iodide of potassium, but not to volatilize any of the latter 
salt. The residue, first permitted to cool, was treated with 
distilled water, and passed through a filter to separate the 
carbon. The filter was well washed, and the solution, hav- 
ing been reduced to a small bulk by evaporation, was pre- 
cipitated by nitrate of silver, and the iodide of silver, first 
edulcorated three or four times with cold distilled water con- 
taining a few drops of ammonia, was finally dried, melted, 
and weighed. 
In an experiment, in which 10.33 grains of the compound 
were employed, the iodide of silver amounted to 7.41 grains, 
equivalent to 3.95 of iodine, or 38.24 for 100 grains of the 
compound. Now, if from this we substract 9.58, the iodine 
in the 12.55 grains of iodide of potassium which we have 
already found to exist in 100 of the compound, we shall 
get for the per centage of iodine, in union with the oil, the 
number 28.66. 
Fearing that the heat applied in reducing the iodate of 
potash to iodide of potassium, might have either been insuffi- 
cient for the purpose, or have volatilized some of the latter 
salt, I recommenced the estimation of the amount of free 
iodine, or rather of that united to the oil, by a somewhat dif- 
ferent process. 
A known weight of the substance was introduced into a test 
tube with water and zinc filing, and the other end being 
drawn out at the spirit lamp, it was hermetically sealed, so as 
effectually to prevent the volatilization of iodine. Agitation 
was now resorted to, and a gentle heat at the same time ap- 
plied, which caused the separation of the oil, the iodine pre- 
viously combined with it having entered into union with the 
zinc, and formed with it a salt dissolved by the water. The 
tube was now broken, and its contents having been thrown 
upon a single filter, previously deprived of all soluble matter, 
