Dr. Inglis’s Extracts from his Prize Essay on Iodine. 17 
tube is filled with the yellow oxide. On raising the tube after 
the combustion has ceased, from the horizontal to the perpen- 
dicular position, a splendid phenomenon takes place; a bright 
red glow of light commences at the bottom of the tube and 
gradually rises to the top after traversing the whole mass. This 
compound Mr. Kemp considers to be an oxide of phosphorus. 
I found that when carbon and dry pure boracic acid are 
heated to redness in a porcelain tube, and pure iodine drop- 
ped into it whilst at this high temperature, a small portion 
of a yellow compound sublimed, which I considered as an 
iodide of boron. * ¥ * ‘i 
When solutions of the protonitrate of mercury and hydrio- 
date of potassa are mixed together, the green protiodide of 
mercury is precipitated; bat by this method a portion of the 
yellow iodide is almost invariably found mixed along with the 
green, on account of the presence of a portion of the perni- 
trate. But this is completely obviated, and a very pure prot- 
iodide formed, when the elements themselves are made to act 
on each other. I found that on agitating together the iodine 
with an excess of metallic mercury in a tube, that combination 
was formed. After the action has commenced, the addition 
of a little water facilitates its completion. This iodide, by the 
combined influence of air and light, is resolved into metallic 
mercury and the biniodide. ‘To try which of these agents had 
the greater power, I placed a portion of the green iodide (being 
perfectly dry) in a closed box impenetrable by any species of 
light. On examining it in a few weeks afterwards, I found 
that it was only partially decomposed, and those portions that 
had undergone the change had assumed a very beautiful ap- 
pearance. There was rising out of the mass at different 
places a formation exactly similar to one 
of vegetable origin: |. represents a small 
mass of green iodide from which the 
‘eryptogamic-looking excrescence sprung; 
2. represents the root, which was of a red 
crimson colour; and 8. is the upper expanded portion, which 
on the exterior was covered with a feathery crystallization of 
the yellow iodide. The interior was hollow, and was exter- 
nally of the same rich red colour as its root. ‘These vegeta- 
tions resembled much in richness and beauty the bells of some 
of the finest heaths. 
Another portion of the green iodide was placed in a small 
phial filled with distilled water, which after being exposed to 
the light for many weeks, still retained its original green co- 
lour, being as yet undecomposed. Air, therefore, is the prin- 
Third Series. Vol. 8. No. 43. Jan. 1836. D 
