No. 6.] president's address b. a. a. s. 351 



ted at 0,000,000 tons, and the by-products therefrom at 500,000 

 tons of tar, 1.000,000 tons of ammonia liquor, and 4,000,000 

 tons of coke, according to the returns kindly furnished me by 

 the managers of many of the gasworks and corporations. To 

 these may be added say 120,000 tons of sulphur, which up to 

 the present time is a waste product. 



Previous to the year 1856 — that is to say before Mr. W. H. 

 Perkin liad invented his practical process, based chiefly upon 

 the theoretical investiiiations of Hofmann, resardins; the coal- 

 tar bases and the chemical constitution of indigo — the value of 

 coal-tar in London was scarcely a halfpenny a gallon, and in 

 country places gas makers were glad to give it away. Up to 

 that time the coal-tar industry had consisted chiefly in separating 

 the tar by distillation into naphtha, creosote, oils, and pitch. A 

 few distillers, however, made small quantities of benzene, which 

 had been first shown — by Mansfield, in 1849 — to exist in coal- 

 tar naptha mixed with toluene, cumene, &c. The discovery, in 

 1856, of the mauve or aniline purple gave a great impetus to the 

 coal-tar trade, inasmuch as it necessitated the separation of large 

 quantities of benzene, or a mixture of benzene and toluene, from 

 the naphtha. The trade was further increased by the discovery 

 of the magenta of rosaniline dye, which required the same pro- 

 ducts for its preparation. In the meantime, carbolic acid was 

 gradually introduced into commerce, chiefly as a disinfectant, 

 but also for the production of coloring matter. 



The color industry utilises even now practically all the ben- 

 zene, a large proportion of the solvent naphtha, all the anthra- 

 cene, and a portion of the naphthaline resulting from the 

 distillation of coal-tar; and the value of colorino" matter thus 

 produced is estimated by Mr. Perkin at £3,350,000. 



The demand for ammonia may be taken as unlimited, on 

 account of its high agricultural value as a manure ; and, con- 

 sidering the failing supply of guano and the growing necessity of 

 stimulating the fertility of our soil, an increased production of 

 ammonia may be regarded as a matter of national importance, 

 for the supply of which we have to look almost exclusively to our 

 gas-works. The present production of 1,000,000 tons of liquor 

 yields 95,000 tons of sulphate of ammonia ; which, taken at £20 

 10s. a ton, represents an annual value £1,947,000. 



