T A N 



Tanker, a perfon who m;uuif;i£tiiix-s liidca and (liins by 

 tanning. 



It is only within a few years paft, tliat the tanners ot this 

 country have been Hberated from a variety of penalties and 

 prohibitions, which were extremely opprelllvc, and long re- 

 tarded the progrcfs of the manufafture. 



Ill the reigns of Elizabeth and James I. when patents of 

 monopoly were in exiftence — when the true principles of trade 

 were not well undetilood — and when the leather manufac- 

 ture was condufted by unllcilful pcrfons, fome rules and re- 

 gulations as to the mode and manner of tanning, the ma- 

 terials to be employed, and the time to be confunied in the 

 procefs, might, perhaps, be in fome degree necelfary : but 

 fuch prohibitions and reltriftions were, wholly inapplicable 

 to the prefent enlightened age. It was not, however, till 

 4808, after a long parliamentary inveftigation, that the aft 

 I James I. c. 22, and others of a fimilar tendency which had 

 long difgraced our ftatute-book, were at length repealed 

 by the 48 Geo. III. c. 60. By this aft, the tanner is 

 now allowed, like all other manufafturers, to exercife his 

 ingenuity in the difcovery of new materials or new methods, 

 in abridging the time or improving the procefs. Nor can 

 any injury thereby arife to the community ; for the compe- 

 tition which in this country exills in every branch of trade, 

 combined with the credit and the intereft of the parties, will 

 always infure to the public the produftion of the belt ar- 

 ticles which can be manufaftured. See Leather, Taw- 

 ing, and Vellum. 



TannerV Bart, is the bark of the oak or other tree, 

 which, after it has been ground in a mill into a coarfe pow- 

 der, is ufed in tanning of leather. When the tanning prin- 

 ciple has been wholl)' exhaufted, it is taken out of the pits, 

 aiid called tan. It is then fold to the gardeners, who ufe 

 it \n hot-houfes to produce an artificial heat, for the pur- 

 pofe of railing pine-apples, &c. After a certain time the 

 tan ceafes to caufe fermentation : it is then taken out of the 

 hot-houfe, and, when entirely rotted, becomes a vegetable 

 mould, and is employed as a manure in kitchen-gardens and 

 on grafs-land. 



With refpeft to its advantages as a manure, different opi- 

 nions are entertained. MiDer, Mortimer, and others, have 

 reprefented it as highly nutritious, while more modern agri- 

 culturalifts confider it of very little value. When, however, 

 it istlended and incorporated with other vegetable fubftances, 

 or with hme or earthy matter in certain proportions, cautioufly 

 employed, and laid on foon after Michaelmas, it will be found 

 a good top-drefling for ftiff and cold grafs-land. 



TANNETE, in Geography, a town on the W. coaft of 

 the illand of Celebes. S. lat. 4° 14'. " E. long. 1 20° 4'. 



T ANNE WANG, a river on the S. coart of the illand of 

 Celebes, which runs into the fea, 5 miles W. of Bonthain. 

 TANNHAUSEN. See THA>ranAUSEN. 

 TANNIN, in Vegetable Chemijiry, a peculiar fubtlance 

 which is naturally formed, and exifts in a great number of 

 vegetable bodies, fuch as oak bark, galls, fumach, catechu, 

 &c. Its name is derived from the eft'eft it has in converting 

 the gelatine into leather. 



Several proceffes have been given to obtain pure tannin, 

 which have been fo various in their refults, as to induce che- 

 rhifts to fufpeft the identity of tannin. 



The procefs recommended for procuring pure tannin, is 

 to powder nutgalls, and make an infufion in water, which wdl 

 be of a deep brown colour. Evaporate th.e infuijon with a 

 gentle heat till it is very ftrong, but ilill retaining its humi- 

 dity. Add to this a faturated folution of carbonate of potafh. 

 A^yellowilh-white precipitate is formed, which is faid to be 



TAN 



pure tannin. When the liquid part is poured ofl', a little 

 cold water mull be added to walh the precipitate, as a large 

 quantity would dilfolve it again. When the precipitate is 

 feparated and dried, it alTumes the appearance of rcfin, having 

 a vitreous frafture. It is of a brown colour. Its talle ij 

 bitter, and (Irongly aftringent. It is very foluble in water. 

 The folution becomes frothy by agitation, as if it contained 

 foap. It dilTolves ftill more plentifully in alcohol. The fo- 

 lution is of a dark-brown colour, diflfering little in its pro- 

 perties and appearance from what has been termed tinfturc of 

 galls. 



For our firft knowledge of this fubftance in a definite ftatc, 

 we are indebted to Deyeux. Scguin afterwards feparated 

 it by means of a folution of gelatme, the matter which was 

 prccipatcd being a fubftance, having the fmell and many 

 other properties of leather. Thefe fads led to the great 

 nnprovements he made in the procefs of tanning, of which 

 no true theory was known before his time. 



For a more minute inveftigation of the properties of 

 tannin, we are indebted to Prouft. He obtained his tannin 

 by adding an acid to a concentrated infufion of nutgalls. 

 A preeipitate is obtained of the confiftency of pitcli. This 

 precipitate is tobewafhedwitha littlccoldwater, withtlic fame 

 caution obferved in the lail procefs. The precipitate is now 

 to be diffolved in boiling water, and carbonate of potafh 

 added, which takes up the acid and precipitates the tannin. 



Prouil recommends the following procefs for procuring 

 pure tannin. Drop into an infufion of nutgalls, a folution of 

 muriate of tin. This gives a yellow precipitate, which being 

 fepai-ated, wafhed, and dried, is of a buff-colour. This is a 

 compound of oxyd of tin and tannin. He then mixes this 

 powder vi-ith water, and palVes through it fulphuretted hy- 

 drogen gas. The fulphur combines with the tin, and 

 becomes infoluble, while the tannin diffolves in the water. 

 When the fulphuret is feparated, and the folution of tannin 

 evaporated with a gentle lieat, a brown fubftance is left be- 

 hind, v/hich he contidercd as pure tannin. 



Another procefs for obtaining tannin from infufion of 

 nutgalls, has been given by Merat Guillot. This confills in 

 mixing pure water with an infufion of galls. If to this 

 mixture dilute nitric or muriatic acid be added, a deep 

 brown precipitate is formed, which, when dry, becomes black. 

 This he fuppofes to be pure tannin. 



Trommfdorff has fhewn that all thefe proceffes are infuf- 

 ficient to produce pure tannin. As the fubftance called 

 extraft was contained in all the above precipitates, and more 

 or lefs gallic acid, he made a great number of experi- 

 ments to obtain pure tannin ; and although he obtained it 

 nearer to a Hate of purity than any of his predeceffors, his 

 labours were not completely fuccefsful. He evaporated the 

 infufion of galls with a gentle heat to one-fourth its bulk. 

 The liquid became muddy from the precipitation of ex- 

 traftive matter, and was feparated by ftraining. It was 

 now" further evaporated to the confiltence of jelly, and ulti- 

 mately dried by a gentle heat. He now digefted the mafs 

 with pure alcohol, till no more gallic acid could be taken up. 

 He then confidered the mafs left behind as pure tannin, or 

 nearly fo. In order to afcertain if it ftill contained extraft, 

 he re -diffolved it in pure water, and evaporated this and 

 future portions of water from it, judging that if any extraft 

 ftill remained it would become infoluble by oxygenation, 

 and thus be precipitated, but no depofition took phice. Suf- 

 pefting it might contain mucilage, he left the folution in a 

 warm place for fome time. It became covered with mould, 

 which he attributed to the prefence of mucilage. The 

 mould was feparated by filtration, and the folution cvapo- 

 L 2 rated 



