52 PRESIDENTIAL ADDRESS — SECTION A. 



is shown by the next photograph, Fig. 28, one of the turbo- 

 generators, occupying a floor space of about 50 feet x 15 feet, 

 and giving 10,000 k.w., or 13,400 h.p. Fig. 29 shows the interior 

 of the Robinson Central Air-Compressor Sub-Station, contain- 

 ing five olectrically-driveii air compressors, having a total of 

 20,000 h.p. The Rand possesses by far the most important 

 system of compressed air distribution in the world, nearly 70,000 

 h.p. being distributed through mains 20 miles long to mines having 

 a distance apart of 14 miles. 



One of the immediate effects of the initiation of this huge 

 power scheme was that, the boiler plant Ijeing suitably arranged, 

 it is possible to utilise fine or " duff " coal, which forms 20 per 

 cent, to 30 per cent, of the mine output, and which had hitherto 

 been considered a waste product and been placed on the dump 

 and burned. Originally obtainable at about 6d. per ton. it now 

 costs about 2s. 6d. at the colliery, but the S.A. Railways, being 

 conducted on so-called business principles, increase this j)rice by 

 over 200 per cent., so that the average cost at the power stations 

 is about 8s. per ton. 



It is painful to think of the many thousands of tons of this 

 valuable fuel still being destroyed, especially in Natal. A few 

 years ago I visited the majority of the Natal collieries, and was 

 so impressed by this terrible waste that on my return I wrote 

 an article, entitled " The Waste of Coal," which was published 

 in the S.A. Mining Journal. But the waste still goes on! 



Readers of technical journals are fully acquainted with the 

 efforts which are now being made to arouse ])ublic opinion on 

 the necessity of fuel economy. Attention is specially directed 

 to the carbonisation of coal in gas works and coke ovens, with 

 a view to the recovery of the valuable bye-products, tar Dud 

 ammonia, from which can be obtained that valuable fertilizer, 

 ammonium sulphate, and the efficient utilisation of the gases ])ro- 

 duced in coke ovens. It is stated that not more than 20 per 

 cent, of the total coal consumed in Great Britain is so used that 

 the bye-products may be recovered. Efforts arc being directed 

 towards the low temperature carbonisation of coal ; it produces 

 less gas and a more friable coke (coalite), but the yield of volatile 

 products is increased. T-rofessor Armstrong urges that the 

 suggested coal-tax should be utilised " in developing suitable 

 methods of coking coal so as to conserve, as far as possible, all 

 valuable products, and at the same time pnxluce fuel for public 

 use." 



He goes so far as to ask " whether drastic action should 

 not be taken to put an end to much of the waste in burning raw 

 coal, at all events in the case of that burnt by domestic users," 

 and suggests a law " forbidditig the use of raw coal for domestic 

 purposes — such enactment to come into force at latest ten years 

 hence." 



