262 MB. JOHN LEIGH ON THE CHEMICAL CHANGES 



injected in a melted state, the neighbouring coal has been 

 subjected to a true distillation, and products are found in 

 the vicinity, the ordinary results of such action. Thus, in 

 Derbyshire, where the measures have been traversed by 

 dykes of trap, popularly called toadstone, springs of naph- 

 tha are found, which must have distilled from the coal. 

 Similar springs are found at Baku, near the Caspian ; at 

 Ammiano in Italy, at Rangoon, and in some parts of Ger- 

 many, &c. The analysis of the fire-damp which streamed 

 out of clefts in the coal at Wallesweille, Luisenthal, and 

 Lickwey, indicated the presence of from 6 to 16 per cent, 

 of defiant gas, according to Bischoff. defiant gas con- 

 tains 2 volumes of carbon and 2 of hydrogen, condensed 

 into 1 volume. In some places, when the coal has been 

 near to the heated matter, it has been found completely 

 charred, and converted into coke. 



In reflecting on these decompositions, there are two cir- 

 cumstances that strike us as remarkable, and which possess 

 peculiar significance. The first and most remarkable fact, 

 is the entire absence of pure hydrogen in any of the gases 

 evolved by the decomposing vegetable niatter, or in any of 

 the fire-damps issuing from the decomposing coal, although 

 so constantly present in coal gas. The second is the equal 

 absence of defiant gas, or of any other compound of carbon 

 and hydrogen, except the light carburetted hydrogen, 

 C H. 2, unless under circumstances that could lead us to 

 believe that the coal had been subjected to a high tempera- 

 ture, and that the higher carburets of hydrogen were true 

 products of distillation, where defiant gas, naphtha, petro- 

 leum, &c., are found as natural products. It will be appa- 

 rent, then, if the foregoing reasonings and remarks be 

 ai^itted as proo^ that it is a law of nature, that when 

 organic masses decompose without access of air — that is, 

 with exclusion of free oxygen — all the elements participate 

 in tho change, and unite reciprocally with each other ; the 



