and Observations on Iodine. 
m 
not been able to determine the elastic force of its vapour. 
Hence the estimations of its composition from experiments on 
the quantity of chlorine absorbed in close vessels must neces- 
sarily be liable to error. In one experiment, in which I dis- 
solved the sublimate, by admitting a small quantity of water 
into the retort, I found that eight grains of iodine had caused the 
disappearance of five and a quarter cubical inches of chlorine. 
In another experiment, in which the sublimate was not dis- 
solved by water, and in which the absorption was judged of 
by the admission of fresh quantities of the gas, twenty grains 
caused the disappearance of 9,6 cubical inches of chlorine, the 
barometer being at 30.1, and the thermometer at 57 Fah- 
renheit. 
It seems probable, from these experiments, that the chlo- 
rionic acid consists of one proportion of iodine and one of 
chlorine. 
The chlorionic acid formed by the sublimation of iodine iii' 
chlorine in great excess is of a bright yellow colour, when 
fused it becomes of a deep orange, and when rendered elastic 
it forms a deep orange coloured gas. It is capable of combin- 
ing with much iodine when they are heated together, its colour 
becomes in consequence deeper, and the chlorionic acid and 
the iodine rise together in the elastic state. 
The solution of the chlorionic acid in water likewise dissolves 
large quantities of iodine, so that it is possible to obtain a fluid 
containing very different proportions of iodine and chlorine. 
The pure solution of the chlorionic acid, when it is very 
diluted, loses its colour by being agitated for some time in 
contact with chlorine, and then, when poured into fixed alka- 
line lixivia or solutions of the alkaline earths, it causes the 
