COAL

Dominion, Volume 11, Issue 280, 15 August 1918, Page 7

COAL

AND ITS BY-PRODUCTS

LECTURE BY PROFESSOR EASTERFIELD

The Technological Section of tho Wellington Philosophical Society was addressed by Professor T. H. Kastcrficld last evening on tho subject, "Tim Distillation of Coal and the liesulting By-pro-ducts." Mr. S. H. Jciikiiison presided. Professor Kastbrfield said,that, supposing coal was heated, four substances always resulted-cokc, tar, watevT and coal gas. Tho quantities of these products depended on tho class of coal. Of coko Jhero would ho from 50 per cent, to 85 per cent. Generally there would be about 5 iper cent, of tar, but there might bo 10 per cent. Tho quantity of coal gas from a toil might bo anything from 4000 to 17,000 cubic feet, though he did not think 17,000 cubic, feet had ever been obtained in New Zealand. Tho coko industry was far older than the gas industry—probably 100 years older. Coal gas was not made as an industry tiil 1809, and then only in small 'quantities. After explaining tho earliest method of making coke, Professor Uasterfield said that the next means was by use of tho beohivo oven, and 'metallurgists raid that there was no coko equal to that made by this method. However, tho yield was not particularly good. .When coal tar becamo u valuable product it was evident that it should be. saved, and ill- tho Jamicsou oven this was effected, and also tho gases, could bo made use of. Theso ovens wero reckoned a great ndvantage, but the tar was not useful for tho purpose the tar-distiller wanted it for. However, to-day that tar.would ho acceptable for use under boilers in tho Kavy, Tho next advance was tho copper oven, and tho oven which followed that also was explained. It would bo sc_en that there was ample room for improvement, and, in fad, frequent alterations were being made. Proceeding, Professor. Kasterfield remarked that ho believed that electricity was being gonerated from waste gases nt a, prico cheaper than the price under «uy hydraulic scheme. But it must be rejuembered that in that caso it was a waste product which was being used. For tho manufacture of coal gas -the horizontal retort was- now looked on as a little bit old-fashioned, and a vertical retort -was considered better. Carbon bi-suluhido was jui absolute bugbear to tho gas manufac turer. It had always been a great trouble to get rid of. The old London Gas Acts specified that the amount of sulphur in the gas should not be more than 20 grains (or thereabouts) to tho If* cubic feet, and in order that that should'be accomplished most elaborate methods were provided for removing the carbon bi-sulphide after production. It was tho in Wellington that when the. horizontal retoris -wero used complaints of sulphur in the gas wero frequent, but with the vortical retorts tho complaints had practically disappeared. There were other advantages with tho vertical retort.

A good many peoplo thought that aniline was a aye. It was not, but the peculiar thing about it was that, whatever chemical it was treated with, it changed its colour. Although thero wore traced of aniline in coal tar, the amount was certainly not more than one part in a thousand, and he should think not more than oho part in 10,000. It was always made' through niiro-beiizinc. Toluene was needed tor the manufacture of explosives, and in England an order had been issued that every works making more than 3,000,000 cubic feet of gas per day must wash all the gas, before it left the works, with tar oil. The result was a great increase in the quantity of toluene available. Professor Easterfield was thanked for his lecture.