Coal=Tar Products

New Zealand Tablet, Volume XXXV, Issue 19, 9 May 1907, Page 11

Coal=Tar Products

The value of products annually manufactured out of materials, which fifty years ago were thrown away as useless waste, amounts at the present time to many millions per annum, indeed, to a yearly sum exceeding the public de]jt of New Zealand. The manufacture of coal-tar products is among the most remarkable of recent industrial developments ; the business is unique in the history of commerce. That a veritable gold mine should ha\e been found concealed tin a factory waste that was exceedingly troublesome and ''difficult to dispose of was like discov-' ering the jewel in the ugly head of the toad or. a realisation of -one of the extravagant dreams of the Arabian Nights. Hundreds of articles now used in the arts and in medicine have their origin in the .black fluid which formerly was only a source of annoyance to those who produced illuminating "gas. In 1856 William H. Perkin, then a youth of 18 years, was assistant to Dr. A. W. Hofmann, a 'distinguished German scientist, who was head of the Royal College of Chemistry in London. The chief made an Easter visit to his native -land, leaving young Perkin in charge of the laboratory. Quinine at that time was very expensive, owing to thn scarcity of the Peruvian bark from which it was > obtained, and the young Englishman was making experiments to determine whether he could secure a substitute from coal-tar aniline. Success did not attend has efforts, however, but while working,, thus alone in the laboratory ,- mixing, testing, and experimenting, he accidentally obtained a dirty, black, unpromising precipitate.

What led him to test its dyeing qualities he has probably forgotten, but he found that, after purifying and dissolving it, the sLuil possessed the**prqpegt:ty of dyeing wool and s^l.c a beautiful violet-line color, which was named mauve. r ihis discovery turned the young Englishman's investigations into another channel, and when Dr. Hoimann returned from h.is vacation he found that his assistant had secured patents and was planning to begin the manufacture of the new dye-stuffs. A factory was erected near Harrow in 1857, and by the end of that year was turning out a heavy output of dye-stuffs. Thus the great aniline dye industry of the world was born, an industry which Germany, France, arid Belgium, especially, 'Lave found exceedingly profitable. Perkin made another great step lorwaid'in 1868, when he began producing the valuable artificial madder, or Turkey-red, on a large scale. Before that the artificial substance was merely a laboratory curiosity and its cost was so great as to be prohibitive. Gigantic Factories. In the same way he laid the foundation of the artificial perfume industry. Early in the seventies, having accumulated a fortune, -he retiitd from business and has since devoted himself to scientifics research. He had started the world, however, uron a new line of industry. German scientists too* up the possibility of coaltar products, and have developed the gold mine persistently and effectively. To day five principal coal-tar product factories of Germany are valued at £'5,000,000. Their output goes to all parts of the world. At one of these 4,500 men are employed, including 1200 skilled artisans, s\iO clerks, 175 engineers, and 145 graduated chemists. The firm owns 1200 German patents and 1400 others through the remainder of Europe and in the United States. One English dye factory employs 4000 workers, including 80 research Ciemists. These examples indicate what an enormous business has sprung from a onceworthless material. Scents for Soap. Benzine is one of the important substances found in coal-tar, having been discovered by Michael Faraday in 1825. It is now used in great quantities for the production of aniline and also a powerful perfume called essence of mirbane, or artificial oil of bitter almonds. No less than 150 tons of this perfume is used annually in Europe for scenting toaps and other toilet articles. The usefulness of bciuine in cleaning goods is known in every household. Another substance found in coal-tar is naphthaline, from which some of the most beautiful yellow to reds, pin s, greens and scarlets are got. Naphthaline is highly prized ay naturalists for p<reserving moths, butterflies, and other insects. Fiom the substance known as anthracene the popular color Turkey red is obtained. Since the time when this was first known, it had been produced from the roots of the madder plant largely cultivated in Russia, Turkey, and France. Alizarin, as the coloring principle of madder is called, has the property of forming various different hues with different chemicals. A piece of calico, printed with several chemicals and given a bath of alizarin, will emerge with different colors — a fact that was mentioned by Pliny. When Perkin adopted by his dye-factory business the discovery of two German scientists that an artificial alizarin could be mad© from the coal-tar product, anthracene, the dyeing and calico-printing industries underwent a revolution. This once despised and rejected coal-tar has also become a corner-stone in the temple of medicine. Its derivations are being extensively useel to cure human ills. For assuaging fevers, antipyrine is effective, and is cheaper than, quinine. It has been used with success in treating typhoid fever and influenza.. Thallium, another coal tar ,drue:, has. especial potency in mitigating yellow fever, phenacetine is used for headaches, cold's, neuralgia, and whooping-cou^h. Sulphonal is popular wjih travellers, especiallythose in countries where hardships and fatigue are the common lot. It produces a deep quiet sleep, lasting seven or eight hours, from which the person awakes refreshed and strengthened. Sweeter than Sugar. One of the most remarkable constituents of this black fluid that comes from coal is saccharine, a substance that is two hundred times sweeter than sugar, and which is useld extensively in the manufacture of candies, fruit, poreserves, jams, and jellies. Saccharine does nioH; fatten as cane sugar does, and for that reason is recommended to persons suffering from certain

diseases, such as diaib.etes. Those who have visited or passed gas works a-nd have seen a tar tank, dirty, repulsive-rooking, emitting a tarry, nauseous odor, would never imagine that here some of the most deligh'itM perfumes of my lady's boudoir have their origin. From coal-tar comes such pleasing scents as ' new-mown hay,' suggestive of sunny fields and buzzing bees ; the ' white heliotropes ' and others so well known and pppular. The same tarry source yields vanilin, a flavoring essence resembling «the best product of the true vanilla bean-; it gives us oil of wintergreen, musk, jasmine, and many others. I'hotography has been aided by tins product of the coal. Pyrogallic acid, metol, hydroquinine, and adural, all extensively used as developing agents-, come from it. So does pyridine, which is employed i,n the deniajtui'ation of grain alcohol. AnUjinionine, another derivative, is used to prevent dry rot in timber. In fact, street paving with wooden blocks has been taken up extensively in European and American cities since it was discovered that remarkajble preservation of the wood was insured by treatment with coaltar substances. Powerful Explosives. And still t|he resources of this wonderful by-product, this waste of former years, are not exhausted. From its derivatives powerful explosives are manufactured — picric acid, lyddite, nieline, maximite, and jovite. Some of these were brought prominently to the world's attention during the Boer and Russo-Japanese wars. Lydddte was first used extensively by the English artillerists in the South African conflict, while the enterprising Japs are said to have employed both this explosive and maximite. Lyddite is, practically, pure picric acid, while melinite, which the French prefer, consists of picric acid modified by 4 per cent of thick, viscid pet'oleum oil. This may be shot through armor plates without detonating by the shock, whi.h lyddite will not do. All these coal-tar explosives raav be handled without danger except from sudden and severe shock. A lighted match dropped amonr; them would not send the man dropping the match soaring skyward, together with a large part of his surroundings, as in the case with' gunpowder. Instead, the substances will bu n freely and as harmlessly as pitch-pine. But when confined in a strong steel shell, find ignited by a powerful detonating charge, their explosive energy is amomr the most fearful of k.»ow n substances. Such, then, in brief is the remarkable record of coal tar. It would seem as though some all-powerful fairy had touched this ugly black ooze with a mystic wand, endowing it with a wealth of possibilities that has ama/ed the chemical world for more than a generation.