96 



buretted hydrogen. It may evolve carbonic acid and form water 

 by union of its hydrogen with external oxygen or from its 

 elements : at any rate it appears coal is wood, that is, carbon with 

 but a small portion of hydrogen and oxygen left : and as we find 

 that the various qualities of coal have more hydrogen and oxygen 

 in proportion as they are less completely carbonised, and that 

 anthracite and graphite, have respectively less and less of a 

 gaseous admixture, we may assume that ordinary coal is still 

 undergoing the carbonising process, and thus evolving carbonic 

 acid and carburretted hydrogen or water. 



But Avhen carbon has arrived at the state in which it exists in 

 coal, that is nearly pure, it may act as pure carbon, that is as a 

 caiTier of oxygen, in the same way that spongy platinum does ; 

 thus the platinum absorbs into its pores oxygen, and if a stream 

 of hydrogen is poured on it, they unite and form water with the 

 evolution of such an amount of heat that the platinum becomes 

 shortly red hot and the hydrogen inflamed. If then the coal is, 

 as we have reason to believe giving forth carburretted hydrogen, 

 and that it is supplied with oxygen from the meteoric water, a 

 union might take place, water be formed and carbon deposited 

 with the evolution of considerable heat, 



I find, by enquiry of mining bailiifs, that deep down in coal 

 mines they say the coal is warm, the intervening rock compara- 

 tively cold and damp, and that this warmth in the coal is more 

 noticeable as you go deeper, where the pressure is greater. 



The deeper the coal the more bituminous it is, and the richer 

 the Shales in its vicinity in bitumen and photogen oils, and as 

 the best opinions say that these oils are due to the action of heat 

 on vegetable matter or coal, or by the decay of those substances, 

 at considerable depths, it would seem that there is evidence that 

 coal has decayed, and its present warmth would indicate that it 

 still is decaying, and undergoing the bituminising process. 



Thus then the mineral salts indicate that the waters of Bath 

 come from some point, probably near Bitton ; that charged with 



