THE NEW TANNING PROCESS.

Nelson Evening Mail, Volume XV, Issue 274, 1 November 1880, Page 4

THE NEW TANNING PROCESS.

(Dundee Advertiser, August 28.) Many of our readers are concerned in the leather manufacture, or io other departments of the leather industries, and are all directly interested, ss constant consumers of commodity, in uny # improvements that may be made in the of cheapening its' productions or rendering it mo^e serviceable in use; end from these circorostanceft, therefore, it may be deemed worth while to tnke brief notice of a new process of tanning which has been creating much anxious attention among the leather traies both et home and abroad. The prooess to ■which we refer to is of German origio, the inventor being a ohfmiefc named Dr Christian H»-icz^rling ; and though it has ouly been brought, prominently under tbe notica of the leather trades within the last twelvemqnlh or so, it bus already been adopted in no fewer than fourteen tanneries in Germany while very recently it has boon brought into practical use in one largo tannery in Russia, nnd in one each in Italy, Paris, anr! Mono, in Belgium. In the last mentioned case the process has baeo f}tfirt.n4 under the auspices of a wealthy banM'gfirm, As another evidence of its valiio, and of the enthusiastic way in which the leather produced by it is petting into actual use, we may mention that about three moot'hs ago there were no fewer than fifty shoemakers uainjj it in the city of Frtnkfort alone. The new process of tauning ia nothing short; of a complete revolution itrthe manufacture of leather. Of course the fame raw material is still used as the •liasis of the manufactured 'article, and fhe great change that has been effected ia one in which the .tanning agents are involved. From time immemorial the pelatine of the lower layer of animal nkins has been converted into leather by ihe use of tannin or tannic acid contained in oak bark, and in recent times ihe bark of many other trees has been brought into use for the same purpose, as also have nutgalls, sumach, valonia, lnyrabolans, catechu, divi-divi, and other products of the vegetable kingdom. .As things are now shaping themselves, there is every prospect that before long euch products will be in compartively little demand for tanning purposes, as ihe new process supersedes them entirely. It does not involve the use of any organic product, but instead, rests its value specially of a compound of inorganic origin, one whose ingredients are obtained entirely from the mineral kingdom. The substance is known in chemical terminology as bichromate of potash, and in commerce chiefly as birchrome — a compound which is manufactured very extensively in the Glasgow district, more extensively, indeed, than any other "part of the world. The essential ingredient— that which exerts tbe desired astringent effect on the animal tissue — is chromic acid, ■which haß to be set free and rendered available in the tanning vat or tank by the ÜBe of other chemical compounds, all of which are readily soluble in water, and none of which are allowed to become waste or refuse matter when they are properly proportioned in accordance with a well known chemical law. (Glasgow Herald, August 26.) One of the greatest drawbacks in connection with the time - honored system of tannirjg leather, that which involves the use of the astringent of oak baik and other vegetable products, is the enormous length of time which is required for the conversion of the raw

hide into the finished material which we know under the name 0/ leather — & substance which is, Co all intents and purposes, a chemical compound of a very complex character, but still of a very definite composition. The time occupied in the production of leather by the familiar and. so-called barktanning process generally ranges from eighteen months to two and a half years, the exact length of time varying according to a nnrr.ber of circumstances, Buch as the kind of hides under treatment, their condition, thickness, &c. ; the kind of tanning materials used, the streugth of the liquors employed, &c. So long as the process involves the use ofexpeusivo plant over such a long period, the raw commodity being a high-priced one to Btarfc with, the finished product roust always be an expensive cn>?, together with tbo articles made of it ; bence, any person who has made euch. ch&ngea ia tliß process of tanaing that it can be thoroughly accomplished in a period of from four to sis weeks may wall be regarded as s public beuefactor. * * * " Having lately paid a visit to the exhibition tannery of tie Eglington Chemical Company, we will now mention sotna'of the interesting; fucis whicli we obtaiaed during our insptciou 01 ihis new process. As it is oily for exhibition purposes, the tannery h naturally on a atnall scale, but it embraces ail the necessary features of such an industrial establishment. Ihaeaie ten email pits or tanks in which the hides are treated, two of them being used for the liming part of tkj process in tbe usual way, The depilatioo, or de-hairing of the hides, is B, so done in the usual wi.y, and hence it need not detaiu us. But after being subject to ihe preliminary operaiioae, and washed .'rtso (rocn tbe lime, the bides are introduced iuto tbe vats, iv wt.icb, there are liquors of varying strengths of bichromate of potash and other chemicals which briflg about the decomposition ol that substance, and so Bet iree the cbromio acid, to txert tha astringent effect that is desired. In tbe course of a week or ten days, (he hides are completely tanned, bo far bb the purely chemical treatment is concerned. They are subsequently made (0 Uke up into their jores a quantity of parafia wax, and are then ready for tbe mechanical treatment, and for currying uud dressing, tbe whole process baing finished in from four to six weeks. In all ordinary respect* tbe resulting leather dots not seem to differ much from bark-'.aaned leather, except thai it has a greenish tinge, which is tlue to tho presence of green seequi-oxide of chromium, resulting from tha decomposition ol some oi the cbroriiio acid. In other respects, however, it ia very different. from the ordinary product of the tai-pit. It ia produced at a less cost tntn barktanned leather ; it is more eiußtic, even after having been wet, much tougher, and more durable; it ia closer anu finer in the grain, and its weight is at least equal to, if cot Bever&l per cent, heavier, tban the product of the baiktunning method. It U the unauimoua opinion of many hundreds of persons who have worn toots made of the ohrome-tanned leather, that they nevei had better boots on their feet, &nd that the leather kept their feet perfectly dry and warm, even though used persistently in tramping through heavy snowt So. far back as the rcooth oi March, there were no few<r than fifty shoemakers in Frankfort alone using the leather, and as many as niae tan neriea had then adopted the process j

and io the conference already alluded to, the President of tbe Shoemakers' Association urged bis bearers to lay to heart the fact that they were at th« 'source of supply, and that they should profit by it, and not put off till the leather was brought from England, for before long minercl-tanned leather from England would be iv the German markets. We understand that the new process is exciting much attention in this country, and that it will be inspected at the Glebe-street Works on Friday. (Scotsman, August 28.) Yesterday, the Egliugton Chemical Company held a semi-public^exhibition in their premises in Glebe Street, Glasgow, of lenthpr which hud been prepared by Dr Heinz rling'd patent process of tautnap; by tntans 0/ bichromote of potash and other miueral substance. A large number of gentlemen connected with the leather trode frora various ports of f he kingdom, »nd several scientific gentleman visited the works and icspected tbe process, tbe leather produced, end articles made of the leuher, such es boots and shore, belling, &.\ Thß chief object and result of tbe p'O'eaa has btea Io reluee the length of tine taken to tan leather t;nd (he cost of its production By the new process leatler oan be prcduced in tbrte or four we^ks, whila by the old it ts»kee from ten to twenty mouths. Besides, in working it a smaller capital and leeß plant are required, a&d tbe cost of proiuction ia bly leseeoei. This company have witbin the List two months produced 300 hidep, and overhead f.ho cost has been calculated nt 1 9-10J per lb of leather, whtreaß by tht» old process the cost rt-nged from 4.1 to 9!. Io addition (0 these advantages it is cloimei that the cure ma process, »s it is called, gives a better yMd of leather, that tbe bother sj produced i much more durable than that produced by tbtt other metboJ, and that I i <es 01 any thickness can be tanned by it'