66 REPORT—1840. 
The discovery of anew mode of decomposing crystallized graphite, by 
heating it in concentrated boiling sulphuric acid, and adding a little con- 
centrated nitric acid*, afforded a series of singular and instructive phzeno- 
mena. After the evolution of binoxide of nitrogen had ceased, each scale 
of graphite was converted into the globular substance before described ; 
its external metallic lustre remaining unchanged, but its bulk so greatly 
enlarged, that what before appeared a single scale, became, by the sepa- 
ration and division of its component laminz, a thick spongy tissue, capable 
of being restored to its former compressed foliated form by the pressure 
of the finger-nail. That this change of form, however, was not merely 
a mechanical effect, appears from the following experiment :—Graphite 
scales having been repeatedly treated with hydrochloric acid, washed, 
and again digested in a strong solution of caustic potash, in order to 
remove all possible mechanical admixtures of iron, silica and alumina, 
were then subjected to the process above described ; the evolution of 
binoxide of nitrogen having ceased, an equal quantity of water was 
added to the mixture ; immediately there succeeded a rapid evolution 
of bubbles from the globules of graphite, which at first lay at the bot- 
tom of the fluid; becoming lighter, as this evolution of bubbles pro- 
ceeded, they gradually rose to the surface, when the gas immediately 
ceased to be evolved ; the acid then, or the graphite, must have been 
combined with hyponitrous acid, which being decomposed by the 
water was disengaged as binoxide of nitrogen. The globules when 
washed, dried, and weighed (at first weighing but 2°01 grs.), had gained 
5°02 grs. in weight. Being then put into a flat covered dish of brass, 
and balanced accurately, the cover was removed, the globules imme- 
diately lost weight, and so rapidly, that in merely removing them from 
the dish, 0°18 gr. were lost ; the dish was covered with a dew, appa- 
rently acid, as it acted on the brass. These globules, heated on paper 
until it became slightly tinged with yellow by the heat, now disengaged 
dense fumes, the paper being streaked with a blackish-coloured smoke 
where it was in contact with the graphite ; 2°30 grs. were lost during 
this process, which being repeated a second time, they were found to have 
lost 2°25 more. Finally ignited in a platinum crucible, dense fumes, 
without any perceptible odour, escaped, the weight of the globules being 
reduced to 1°86 gr. After which, no further reduction took place during 
the ignition for half an hour in the open air. The total loss of the two 
grains thus experimented upon with the acid, was 6°96. In a paper by the 
author‘, this loss was attributed to evolution of carbonic acid gas during 
this conjoined action of the acids; but it would appear from the last 
experiment, that there is formed a compound of sulphuric acid, nitric 
acid, carbon, hydrogen and oxygen, volatilized only at high tempera- 
tures. The question here arises, how can the rapid loss of weight be 
accounted for? During the previous drying process, which was con- 
ducted at 212°, the loss of water must have been accompanied by a 
change of chemical composition, and the new compound, by attracting 
* See a description in the Philosophical Magazine, vols. xvi., xvii. 
+ See Philosophical Magazine, cited above. 
