10 DR TRAILL ON THE TORBANEHILL MINERAL. 



a. Yielded 27*5 residue, and 72-4 per cent, was dissipated. 



b. „ 21-4 „ „ 78-6 „ 

 c „ 15-9 „ „ 84-1 



One hundred grains of Bitumenite afforded by distillation 60*5 cubic inches 

 of inflammable gas, which is equivalent to rather more than 274 cubic feet per 

 cwt. ; and this gas had a far greater illuminating power than the best coal gas I 

 have ever examined. I considered it in this respect to approach nearer to oil gas 

 than to common coal gas. I did not, however, determine the comparative illu- 

 minating power by the best test, chlorine, but estimated its superiority by the eye. 



Besides this, the distillation afforded a considerable quantity of the chemical 

 compound known by the name of Parqffine, a substance now used to grease ma- 

 chinery, and for other economical purposes; a product which I have not ob- 

 tained from coal when distilled for gas. 



I am well aware that by a slow distillation with a moderate heat, Paraffine 

 may be procured from certain kinds of coal, from peat, from bitumens, and per- 

 haps from every substance capable of yielding defiant gas, or what has been 

 termed Bicarburetted Hydrogene ; for their atomic constitution seems to be nearly 

 similar = C 4 + H 4, or some multiple of these. This substance has been manufac- 

 tured in large quantities from Bitumenite by Mr Young, as the specimen on the 

 table will shew. 



By distillation, too, petroleum may be obtained from it, especially if the mi- 

 neral be first allowed to imbibe as much water as it can absorb ; and this pro- 

 duct is more abundant, more than is yielded by any coal. The fixed residue of the 

 combustion of Bitumenite consists chiefly of silex and alumina, with traces of 

 lime and oxide of iron. 



Bitumenite occasionally contains casts of vegetable remains, especially of 

 large Stigmarice. A very magnificent specimen of Stigmaria in Bitumenite, as 

 thick as the human body, has been deposited by Dr Christison in the University 

 Museum. In examining the structure of thin slices by the microscope, I per- 

 ceived where the organisms occurred some traces of vegetable structure ; but in 

 other portions of the mineral I was unable to perceive the least trace of organic 

 structure. In several specimens, in the hands of Mr Sanderson the lapidary, I 

 was also unable to see real organic structure ; but observed numerous globules of 

 a pale yellowish matter, which I take to be bituminous particles disseminated 

 among the opaque earthy ingredients. 



But even if such organic texture could be traced in every part of it, still this 

 would not constitute it a coal ; for organic structure is constantly seen, too, in 

 mineral charcoal, in surtarbrandr, in peat, and in petrified wood ; yet nobody 

 would denominate these varieties of coal. 



