COAL-TAR AND ITS BY-PRODUCTS.

Ashburton Guardian, Volume xxix, Issue 7240, 27 July 1907, Page 4

COAL-TAR AND ITS BY-PRODUCTS.

A lecture was given on Wednesday by Professor Easterfield in the Wellington Town Hall on the subject of "Coaltar and its by-products." The lecturer commenced with a brief historical sketch of the discovery and developments of the products of coal-tar, liottman, a pupil of the great German chemist Liebig, and the first director of the Royal College of Chemistry in London, investigated the properties of coaltar, and succeeded in isolating a large number of substances, while his pupil, Mansfield, carried the research further, and might have anticipated later developments had not his career been cut short by an explosion of benzine, winch he was preparing for the Exhibition of 1851. His methods of distillation are still employed in the manufacture of aniline and other by-products of tar. The lecturer, showed experimentally by fractional distillation how benzine, tiie chief of coal-tar derivatives, was obtained. From this light oil and not from aniline, were manufactured the beautiful colours which gb under the name of aniline dyes. The inflammability of benzine was demonstrated by an explosion inside a copper vessel. Benzine treated with nitric acid formed the base of most of the coal-tar colours, and was used to perfume the majority of Brown Windsor soaps. It was from nitro-benzine that Perkin, then a boy of 17, and a student under Hoffman, managed to isolate aniline and discover the dye, which he patented in 1856 as mauve. Seeing the possibilities in coal-tar, Perkin at once left the college and started .the manufacture of aniline dyes. The jubilee of the discovery was celebrated last year, and the inventor knighted. He died at a ripe age a few weeks ago, having devoted the latter part of his life to experimental science and research. Professor Easterfield then, by the addition of various re-agents to nitrobenzine, prepared a number of beautiful dyes, some of which, he admitted, lacked the quality of permanence. From phenol or carbolic acid he obtained other colours. , Phthalic acid, another by-product of coal-tar had revolutionised the manufacture of indigo, and ruined the planters in India. In'the same way the discovery of alizarine had driven vegetable matter out of the market. Saccharine, also manufactured from coal-tar, had the property of being five hundred times as sweet as sugar. Picric acid, the base of the explosive known as melinite, which was so much used in the Boer war, was obtained by the lecturer from a solution of pherol in strong sulphuric acid, to which ho, added a few drops of hydrochloric acid. It was much used, said Professor Easterfield, as a dye, and also, though illegally, to (live bitterness to beer. In concluding his lecture, which was plentifully illustrated by diagrams and exneriments, Professor,Easterfield emphasised the value of research work in science as of,the greatest .importance in the progress of nations.—Evening 1 Post. ■ :..