DECAY OF WOODY FIBRE. 343 



origin and formation of diamonds, except the process of decay. 

 Diamonds cannot be produced by the action of fire ; for a high 

 temperature, and the presence of oxygen gas, would call into 

 play their combustibility. But there is the greatest reason to 

 believe that they are formed in the humid way — that is, in a 

 liquid, and the process of decay is the only cause to which their 

 formation can with probability be ascribed. 



Amber, fossil resin, and the acids in mellite, are the products 

 of vegetable matter which has suffered eremacausis. They are 

 found in wood (or brown) coal, and have evidently proceeded 

 from the decomposition of substances which were contained in 

 quite a different form in the living plants. They are all distin- 

 guished by their proportionally small quantity of hydrogen. The 

 acid from mellite (mellitic acid) contains precisely the same pro- 

 portions of carbon and oxygen as that from amber (succinic 

 acid) ; they differ only in the proportion of their hydrogen. 

 Succinic acid may be obtained by oxidation from wax and all 

 other solid fats, 



