Pro/. T. Rupert Jones — Address. 



561 



Table showing the Output of Coal in the South Wales District in the Years 

 1880 a7id 1890. 



Total Output for the United Kingdom. 



Dr. E. Hull refers to the increased production in the South-Welsh Coal-field, 

 too-etherwith remarks on other fields and the future supply and working of coal, 

 in°the "Transactions of the Edinburgh Geological Society," vol. yi. part 2, 1890 

 where also Mr. H. M. Cadell follows with valuable notes on the probable future of 

 the coal-trade. , , ., . 



7. Varieties of Coff?.— The coal of the British Coal-fields exhibits every variety 

 of composition between anthracite, which is nearly pure carbon, and the so-called 

 bituminous coals, such as ordinary coal and cannel coal (hydrocarbons), rich m 

 hydroo-en. Anthracitic beds are rarely seen except in districts where the strata have 

 been much disturbed, or peculiarly affected by other circumstances-. Heat, whether 

 direct or induced by pressure, vertical or lateral, has probably been the important 

 ao-ent in depriving coal of its hydrogen with some of its carbon, and thus changing 

 it°into authracite. Neither in this latter nor in the compact cannel coal are^the 

 laminar structure and symmetrical jointing so distinct as in the ordinary coals. The 

 last lose their volatile hydrocarbons also by exposure to the air, at outcrops and in 

 open faults ; hence they are not nearly so good for burning as those got at a greater 

 depth. As it is well to have definite notions as to the appearance and structure of 

 the different kinds of coal, some notes on the several sorts will now be offered. ^ 



Anthracite is glossy or semi-lustrous, sometimes iridescent ; it ignites with 

 difficulty, and burns without smoke, and with little fiame, on account of no volatile 

 hydrocarbons being formed during combustion. This purely carbonaceous material 

 differs from ordinary coal by its brilliant, semi-metallic lustre, its greater density, 

 hardness, and brittleuess, and by its massive and conchoidal fracture with sharp 

 edo-es Some of it can be cut or turned on the lathe into fancy articles. 



Called anthracite (from Si/9pa|, coal) by Karsten and the older mineralogists 

 it is also known as mineral carbon, blind-coal, stone-coal, culm, glance-coal, and 

 non-bituminous coal. It is mentioned by mineralogists and geologists as having 

 been fouud at many places in the Alps, Pyrenees, France, Germany, the United 

 States and the British Isles, under various geological conditions; but in regular 

 and extensive beds it occurs chiefly in Pennsylvania, and largely also m South 

 Wales It is reported to have been found in China and elsewhere. 



In the Franco -Belgian coal-field the coals become more and more anthracitic as 

 they pass down to gr'eater depths ; both kinds, therefore were of the same age in 



1 Much information as to the constitution of coal and its_varieties is given in 

 Eoland and Richardson's Chemical Technology. 



DECADE III. — VOL. VIII. NO. XII. 36 



