5^9 
Combustion of the Diamond, 
probable that the same corpuscular arrangements which give 
to matter the power of transmitting and polarizing light, are 
likewise connected with its relations to electricity ; and water, 
the hydrates of the alkalies, and a number of other bodies 
which are conductors of electricity when fluid, become non- 
conductors in their crystallized form. 
The power possessed by certain carbonaceous substances of 
absorbing gases, and separating colouring matters from fluids, 
is probably mechanical and dependent upon their porous na- 
ture ; for it belongs in the highest degree to vegetable and 
animal charcoal, and it does not exist in plumbago, coke, or 
anthracolite. 
The same conclusions respecting the composition of carbo- 
nic acid may be drawn from these experiments, as from those 
of Messrs. Allen and Pepys, and Theodore de Saussure. If 
the calculations be founded upon the difference of the weights 
of oxygene and carbonic acid gases, which appears the most 
exact method, carbonic acid gas will contain, according to the 
estimate of the mean specific of the gravities of the two gases 
given by M. Theodore de Saussure,* thirty parts of oxygene, 
or two definite proportions, to 11.3 parts of carbon, or one 
definite proportion. 
Supposing the diminution of the oxygene produced in the 
experiments on the common carbonaceous substances entirely 
occasioned by the formation of water, it is easy to calculate 
the proportions of hydrogene in them ; but in the case of 
plumbago there is probably a diminution of oxygene, from 
the oxidation of the iron ; and it is not certain that the ashes 
* Annales de Chimie, Tome LXXI. pag. 261. This estimation is the same as that 
I have given. Elements of Chem, Phil. pag. 305. 
