W. Skew — On the Evolution of Sulphur from Carbon. 389 



(3.) That torbanite is not coal, but a chemical combination of an acid 

 hydrocarbon with silicate of alumina. 



(In this assumption I accept for the present the popular opinion which 

 maintains the ash of coal itself to be an accidental element.) 

 (4.) That our present formula for torbanite requires amendment so as to 



include earthy matters. 

 I will only add that, judging from the basic nature of alumina and the 

 refusal of silica in any form to combine to a notable extent with any of the 

 constituents of petroleum, it appears most likely it is the alumina of the 

 earthy matters of torbanite to which the retention of its combustible part is 

 due. This matter, and the possibility or otherwise of substituting compounds 

 of tin, iron, copper, etc., for that of alumina as absorbents of the substances 

 named, is now engaging my attention, and so I trust to be able to give infor- 

 mation upon these points at an early date. 



Art. LXIII. — On the Evolution of absorbed Sulphur from Carbon by Voltaic 

 Action; with Notes upon the Rev. II. Ilighton's Theory for explaining 

 the Evolution of this Gas from certain Batteries in Work. By William 

 Skey, Analyst to the Geological Survey of New Zealand. 



[Bead before the Wellington Philosophical Society, 21st November, 1874.] 



In a paper read before this Society in 1870 upon the " Electromotive 

 Power of Metallic Sulphides,"* I stated that graphite freshly prepared is 

 negative to sulphurized graphite, and I observed that during the time 

 sulphurized graphite is connected with zinc it evolves sulphuretted hydrogen. 

 But viewing this phenomenon as only one of a series I had already decided t 

 I did not state it specifically, though that I must have noticed it is, I think 

 undeniable to any one who may go over this paper. 



I am thus retrospective for once, and somewhat explanatory, as it happens 

 that since the communications I have referred to were made, the Rev. Mr. 

 High ton, in the course of one of his numerous and important electrical experi- 

 ments, has observed that an evolution of sulphuretted hydrogen takes place 

 under circumstances very similar to that I have already described. Thus this 

 gentleman ascertained that graphite paired with zinc in an exciting fluid of 

 sulphuric acid gave off sulphuretted hydrogen j and it is particularly the origin 

 of the gas in this last case which I am anxious to discuss here, as there 

 appears to be a very great diversity of opinion upon it j and what especially 



* Trans. N.Z. Inst., III., p. 232. 



ans 



form 



