RECAPTURING CHEMICAL TRADE

Nelson Evening Mail, Volume L, Issue 175, 2 November 1917, Page 6

RECAPTURING CHEMICAL TRADE

DYES AND DRUGS.

There /was a time when 'Great Britain was to the very forefront in the manufacturing of chemicals, but owing to the thoroughness and persistency of the attack that had been made for many years by the German captains of the chemical industry she gradually lost her grip, and thus when war broke out in 1914, and the German supplies were cut off ,many trad'es that had been dependent for their own existence orr chemicals then made almost solely - by the enemy were threatened with extinction. The whole subject is dealt - with in an supplement of tie Manchester -Guardian. To this paper authoritive articles are contr buted by a number of distinguished scientists, among them Professors HF;'Armstrong, A. G. Green, W. H. Perkin, W. J. Pope, Mr L. E. Vlies, and Dr. C. W. Saleeby. As it would be impossible, however, to do m a brief abstract to'subjects covering such a wide range, it will bo only the synthetic dye stuff industi-ies and the singular relationship that exists J 36 " tween some synthetic drugs .and dye stuffs that will be touched on here. Indigo and the indigoid class are the most important of the vat dyes, and in the manufacture of these practically nothing was known in Great Britain before 1914. A vat dye, it may be explained, is an inert substance that, being insoluble in water, _ requires a reducing agent to bring it into solution. A peculiarity of it, too, is that when the drying process has been completed the colour of the fabric does not always represent the ultimate effect. The fabric, for instance, may be bright blue when it is taken from the vat, vet by subsequent treatment it may be changed to a brilliant yellow Indigo is at the head of the class, and though the indigoids resembled it chemically they may differ widely from the dark purple-blue that we associate with indigo. Thus an important indigoid is a rich red; another is a glowing scarlet. It was the discovery of thio-indig6 red by Professor Friedlander in 1905 that gave an impetus to the production of indigoids. Not long after that the new method discovered in 1907 of combining bromine with indigo greatly aided the chemist in producing newdyes. The English chemists have had an immensely difficult task in undertaking the manufacture of many of the vat dyes, because, while they had everything to learn ,the field! was one that the Germans had been hard at work cultivating for 15 years. The chemical processes involved are extremely complicated, nor did the patent records afford much information as to their nature; indeed, it is auite in character with German commercial methods that many of the specifications were drawn up apparently for the express purpose of misleading inquirers. But fair, progress hac already been made. Morton and Co., the •Glasgow dyers, are producing enough indanthrene blue for their own requirements, and in Manchester this and other vat dyestuffs are being manufactured on a large scale. All the indigo needed by the naval and military authorities has been supplied by Levinstein Ltd., Manchester, though Dr Levinstein admits that the brilliant alizarine blue used for some parts of naval uniform is beyond his experts at present, and that it could be obtained only in Germany. But the firm was able to supply within a week all. the khaki dyei required for the Australian uniforms and the green for the Italian army's unifoim; on the same firm, too, 'Russia was indirectly dependent,' for Russia obtained equipment in vast quantities from the United States, and it was from the Levinstein works that the American contractors got the dyes required. In passing, it may be mentioned that, though we may depend to-day almost altogether on coal tar derivatives for our dyes, the "art" of dyeing as distinguished from the "trade" of dyeing is not yet lost. One of the contributors to the supplement mentions how, some years .ago, he visited a woollen mill in Wales. The beautiful colours of the fabrics appealed to his artistic instinct, anb, asking the ''proprietor where he obtained them, he •was surprised to learn that the leaves, barks, roots, and flowers required for mox-clants and dye stuffs were all growing in the mountains and valleys of the country side. "Though much has been done by private- enterprise, Professor Green holds i that, the difficulties under which the 'English dyestuff industry must labour foii a time can only be met by a mea/syjre of State assistance. Whether this >*hould take the form of an import duty, ~( < jff,, a direct subsidy to the producer, ' or" of a complete partial prohibition upon imported dye stuffs is a matter open, to great differences of opinion. such help, however, during its period of growth the reinstated dye stuff manufacture cannot establish a

satisfactory position, even although, as well may be the case, the German industry does not regain its pre-war efficiency for several years. 'There is a strange relationship between synthetic dyes and synthetic drugs that Professor Ehrlich was the first to discover. In 1913, at the International Medical Congress in London, Ehrlieh's little pale, grey figure was the cynosure of every eye, his discussion of salvarsan, his great creation, at St. Thomas's Hospital, reduced indeed all the rest of the congress to insignificance. The key to Ehrlieh's success, both with salvarsan itself and with the later parasiticide, trypaflavin (an antiseptic that has been of the greatest value in the treatment of wounds), is to be found in the precise chemical study of the dye-reactions of the particular parasites which he sought t-o fight. The disco-very of the parasites in question was followed by the discovery of the particular dyes which would reveal them. It was Ehrlich who perceived, as Dr Saleeby points out, that the relation between a dye and a particular type of cell is a chemical fact which may have the highest therapeutic significance. All such dyes must be studied for each type of parasite that concerns therapeutics. Each dye must be regarded as an agent that will pierce or fix the parasite in question. In Ehrlieh's own figure of speech, the drug he desires is like a poisoned arrow. The point of the arrow is the particular dye, which Has a selective affinity for the parasite, and therefore fixes it. If to such a dVe or the effective part of "radicle" of such a dye there can be attached a poison, then the arrow will be not only a dye but the parasite we desire. Dyes and drugs must, therefore, be thought of together henceforth. The study of dyes in their relations to the parasites, Dr Saleeby continues, led Ehrlich to make his synthetic drugs; and to-day the resources of the maker of synthetic dyes are those upon which the maker of synthetic drugs depends. Ehrlich constructed salvarsan as a drug which would have chemical affinities resembling those that certain dyestuffs have for cotton, and that should convey to the parasites, thus fixed, arsenic ,in doses which could not possibly be introduced otherwise into the human body. Salvarsan and its successors do all that Ehrlich asserted, and more. The animal forms offered the best hopes, and so he concerned himself with trypanosomes, which are the cause of sleeping sickness, and which are not very far, in a zoological classification, from the spirilla of syphilis, yaws, and relapsing fever. He gave directions accordingly for the construction of a new compound of a certain molecular constitution, which was found to have a specific action upon trypanosomes, and this compound, having a yellow colour, he called try pa-flavin Dr Ehrlich died recently. It is interesting to learn that, though a German professor, he detested Prussianism, and that, notwithstanding his great name, greater than ever after his discovery of salvansan and that incomparable antiseptic trypa-flavin, he was anything but persona grata with the Prussian Court.