250 PEOF. A. H. GKEEN Olf THE GEOLOGY A^^I» 



Others less transparent and of a darker brown (? vegetable matter 

 mixed with mud); others deep black and opaque (? mud-films) ; these 

 last were most sharply defined. I made comparisons with the follow- 

 ing coals, sections of which were kindly lent to me by Mr. E. T. 

 Newton : — Newcastle; Babington Colliery, Notts; Moira ; Wharn cliff e 



Fig. 1. — Diagram illustrating the Structure of the South- 

 African Coals. 



Silkstone, Barnsley. More or less lamination was recognizable in all 

 these, but in all it was inferior in fineness, distinctness, and evenness 

 to the lamination of the Cypher Gat coal. I also noticed the eflfect 

 of increased enlargement on the difi'erent sections. Under a power 

 of 200 diameters the lamination of the Cypher Gat coal is more 

 sharp than with lower powers, and the fine black stripes especially 

 stand out more conspicuously. The reverse was the case with ihe 

 English coals ; under the higher power their lamination became 

 confused and indistinct. In the English coals, too, the laminse did 

 not differ so much in transparency as in the Cypher Gat coal, and 

 there were none of the fine black laminse. 



The differences are not great, but they are such as might well 

 arise if the African coals were formed under water into which 

 vegetable matters and mud were discharged. Even when the vege- 

 table matter was in excess, there was still mud enough present to 

 cause the coal to contain a large percentage of ash ; at other times 

 the supplies alternated in rapid succession, so that only very thin 

 laminae of impure coal were deposited, and on the top of each a thin 

 film of black mud was spread out. 



Other singularities are presented by coals from Van Yyk's Earm 

 near Burgersdorp, and Yan Zyl's Farm near Molteno. The analyses 

 of these coals and of the coal from the Indwe are subjoined ; — 



