Reviews — The Mineral Industry of South Africa. 427 



VI. — The Mineral Industry of the Union of South Africa, and 

 its Future. By P. A. Wagner. South African Journal of 

 Sciences, September, 1918. pp. 34, with a map. 



fPHIS is a reprint of Dr. Wagner's Presidential Address to 

 I Section B of the South African Association for the Advancement 

 of Science. It consists essentially of two parts, the first being a 

 comprehensive review of recent developments in the mineral industries 

 of the Union, while the second part is maialy devoted to the future 

 and the possibility of further discoveries. It is difficult to know 

 what to select for special comment from the great mass of valuable 

 information contained in the first part, but one or two points may be 

 briefly mentioned. Dr. Wagner takes a distinctly optimistic view as 

 to the development prospects of the metalliferous deposits of the 

 great Insiswa intrusion in Zululand, which may perhaps turn out to 

 be a notable rival to Sudbury. This appears to be an excellent 

 example of gravitative differentiation accentuated by the im- 

 miscibility of sulphide and silicate magmas. Another local industry 

 which has of late actually reached a position of world-wide importance 

 is asbestos mining. South Africa now leads the world in the 

 production of this useful mineral, as also of corundum. It is 

 interesting to note that the phosphates of Saldanha Bay are now being 

 actively exploited on a large scale with successful results. With 

 regard to the phosphate beds in the Ecca Series in Natal, it might 

 have been mentioned that these were described by Dr. Hatch nine 

 years ago in his Report on the Mines and Minerals of Natal. South 

 Africa is now beginning to take a place among the iron-smelting 

 countries of the world, four blast furnaces being now in operation. 



The second part of the address is occupied by a consideration of 

 the geographical distribution of minerals : the Union is divided into 

 nine provinces, mainly based on geological formations. It is pointed 

 out that large tracts of country are still virtually unprospected, 

 and the future may yet hold surprises in store, though probably 

 nothing equalling in importance the diamond pipes of Kimberley 

 or the Band goldfield remain to be discovered. Yet there is 

 alwavs hope. 



R. H. R. 



VII. — Notes on the Formation of certain Rock-forming Minerals 

 in and about Glass Furnaces. By G. V. Wilson. Trans. Soc. 

 Glass Technology, vol. ii, pp. 177-216, 1918. 



f PHIS paper contains an account of some interesting and important 

 X observations made by the writer in connexion with recent work 

 on glass-making in Scotland. The opportunity was afforded for the 

 most part by the accidental bursting of a tank furnace at the Kinghorn 

 Bottle Works in Fife ; the molten material, amounting to about 

 70 tons, flowed into a space below the furnace and took several days 

 to cool. During this slow cooling several types of crystalline 

 material were formed and reactions took place between the molten 

 glass and the bricks of the furnace, leading to the formation of a 

 series of minerals, mainly silicates of lime and alumina. Other 



