All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

All About Inventions as to jeopardise the extension of this method of illumination. It is impossible to trace the romantic story of coal-gas within the compass of a single chapter, but there are certain milestones in the history of its development which are of more than cursory signifi- cance. In the early days the gas was the solitary article in demand. The other products which arise during the process of distillation were regarded as an unmitigated nuisance. But as the industry settled down, owing to the successful surmounting of the initial problems, and scientists realised that coal-gas, instead of being a dire enemy, was an invaluable friend, offering a remarkable field for investigation and research, the waste products claimed greater attention. First it was found that the solid residue in the retorts, the coke, which remains after dis- tillation is carried out, was not a useless ash or clinker, but that it still retained valuable fuel properties, and was virtually as good for power and heating purposes as the original coal. In some respects it was superior to the latter article, and possessed the overwhelming virtue of emitting no smoke during combustion. Then the viscous black liquid which issues from the coal was discovered to be a valuable wood-preserving agent, one of the earliest applications of this residue being the impregnation of sleepers for railways and the butts of fence posts, which it was found, when treated with this substance, possessed longer lasting qualities than the raw timber. But the great advance was made in 1856, when a young research chemist, eighteen years old, discovered the first of the aniline dyes—mauve. By this achieve-