14 Dr. Inglis’s Extracts from his Prize Essay on Iodine. 
tendency, however, is still to regain its original capacity, so 
that any substance containing hydrogen, or any other element 
which combines with the chlorine or iodine, instantly liberates 
the nitrogen, and it expands with a force equal to that which 
would be required to liquefy it. * * * * 
There is but one hydrocarburet of iodine noticed by authors; 
it appears in colourless acicular crystals, and is formed by the 
action of olefiant gas on iodine. Faraday, its discoverer, 
found it, in composition, quite analogous to chloric ether, and 
called it hydrocarburet of iodine +. 
After having thoroughly dried a portion of iodine I intro- 
duced it into a flask, which was luted on to a gas tube with 
sulphate of lime; then the stop-cock was opened, and a constant 
supply of gas was thus allowed to enter as fast as the former 
was absorbed. Instantly there.is action observed; the small 
grains of iodine on the sides of the vessel become semifluid, 
and of a dark colour, and the interior of the flask is gradually 
filled with ruddy brown fumes. In the course of four hours, 
the acicular colourless crystals of Faraday began to appear, 
and that in the shade, showing that the direct rays of the sun 
are not necessary, as he supposed}. After the gas had been 
acting on the iodine for eighteen days I removed the flask, and 
observed a fluid at the bottom, which when examined was of 
a blackish green colour. It does not combine with water, but 
runs into globules like oil, or more exactly like a solution of 
iodine in creosote when it is placed in water. On the appli- 
cation of the leat of a spirit-lamp to a tube containing this 
fluid with the mixture of a drop or two of water, slight ex- 
plosions take place, the black liquid is decomposed, a red 
fluid rises in vapour, and olefiant gas is evolved. ‘The red 
fluid is probably a mixture of olefiant gas and free iodine, for 
it instantly casts with starch the characteristic blue tint. 
When the black fluid is put into a small retort, and heat 
applied, olefiant gas is first driven off, and then a copious ef- 
fusion of hydriodic acid; whilst at the same time the orange 
red fluid again appears. When the beak of the retort is 
placed in water the hydriodic acid is absorbed, and portions 
of the red and black fluids come over also; the latter falls ot 
the bottom. The water precipitates starch blue, and the per- 
chloride of mercury instantly causes the precipitation of the 
periodide of mercury. Alcohol removes the substance that 
keeps this compound fluid, and the solid green hydrocarburet, 
+ See Phil. Trans. for 1821 : or Phil. Mazg., vol. lix. p. 852.—Enir. 
} Mr. Faraday certainly formed this compound by exposing iodine and 
olefiant gas to the sun’s rays, but he does not explicitly represent that the 
“ direct rays” are necessary.—Epir. 
