318 MINERALOGY. 



COMBUSTIBLE MINERALS. 



Combustibles form a class of substances of properties 

 peculiar to themselves, but possessing in common only the 

 property of combustion ; the bases of combustioDj as we 

 before remarked, are two. Sulphur and Carbon. 



Sulphur is a soft brittle substance, of a pale greenish yellow 

 colour ; it is found in masses, sometimes in veins, and 

 at others in large beds ; it is obtained from the Animal 

 and Vegetable as well as Mineral Kingdom. 



The uses to which Sulphur is applied are various, and so 

 well known as not to require enumerating ; it is highly 

 inflammable, and is about twice the weight of water ; it gives 

 out an odour peculiar to itself when rubbed; it burns with 

 a blue flame, and the vapour it exhales when ignited, is par- 

 ticularly injurious to animal life. 



Cakbon. The Diamond, which is considered as the hardest 

 substance yet discovered, is capable of being com- 

 pletely dissipated ; if heated to the temperature of 

 Molten Copper, and subjected to a current of air, it 

 becomes gradually but completely combustible, by 

 •which process it may be entirely converted into Car- 

 bonic Acid.^ 



