Sir H. Davy's Experiments on the 
That charcoal is more inflammable than the diamond may 
be explained from the looseness of its texture, and from the 
hydrogene it contains ; but the diamond appears to burn in 
oxygene with as much facility as plumbago, so that at least 
one distinction supposed to exist between the diamond and 
common carbonaceous substances is done away by these re- 
searches. 
A fact which I formerly noticed, the blackening of diamond 
by the long continued action of heated potassium, induced me 
to suspect in the beginning of these inquiries, that common 
charcoal might owe its colour, opacity, and conducting power, 
to the circumstance of its containing minute portions of the 
metals of the alkalies, or earths, and plumbago to the iron it 
contains ; but when I found that charcoal made from oil of 
turpentine, which left no residuum in burning, and charcoal 
precipitated from carburetted hydrogene gas by chlorine, 
had the same properties, it was necessary to renounce this 
opinion. 
The only chemical difference perceptible between diamond 
and the purest charcoal, is that the last contains a minute por- 
tion of hydrogene ; but can a quantity of an element, less in 
some cases than Yo ' doo weight of the substance, 
occasion so great a difference in physical and chemical cha- 
racters ? This is possible, yet it is contrary to analogy, and I 
am more inclined to adopt the opinion of Mr. Tennant, that 
the difference depends upon crystallization. Transparent solid 
bodies are in general non-conductors of electricity, and it is 
were long heated in glass tubes, the one in contact with diamonds, the other alone, 
that in contact with the diamonds must have acted upon a much greater surface of 
glass. 
