TANNING. 



jcd, tliat the art of tanning was thoroughly underAood, and 

 reduced to fcieiitific principles. Ho inllitutcd a fcrics of 

 experiments on the various fubftances employed — exjmined 

 their chemical affinities and agencies — their aftion upon 

 animal matter, and combination with other bodies — and 

 developed and explained the whole with a firaplicity and 

 perfpicuity which forcibly elucidated the effential principles 

 on which the art depends. If this elucidation has not been 

 produftive of any materia! improvements in the mode of ma- 

 luifafturing leather, it may perhaps be attributed more to 

 the prejudices ariflng from long habit, than to any defett 

 in the tlieory and demonilrations of that enlightened philo- 

 fopher. And here it may be remarked, tliat thefc demon- 

 ftrations and that theory derive additional importance, and 

 are entitled to peculiar attention, from having been ftrongly 

 confirmed and fuccefsfuUy praclifed by an intelligent and 

 refpcftable manufadlurcr (now retired from buiinefs), to 

 whom we are chiefly indebted for this' article. 



From thefe and other fources of information now open 

 to the public, and from the general diffufion of knowledge • 

 among all clalTes, the man of fcience and the mannfa6lurer 

 are daily becoming more affimilated to each other ; and if 

 the latter Ihould be taught to difcard all unfounded preju- 

 dices, and to adopt more fcientific principles, there is reafon 

 to believe that the various procefTes of the art of tanning 

 may yet be capable of great praftical improvement. 



In the two valuable papers which fir Humphrey^ Davy has 

 given in the Philofopliical Tranfaftions for 1 803, he confiders 

 the procefs of tanning as depending fimply on the chemical 

 ■ imion of the tanning principle with the matter of ikin, fo 

 as to form an infoluble compound. He lias fhcwn that 

 Seguin's quick method of tanning is not the befl ; becaufe 

 the exterior ftrata of il<iu being perfeftly combined with 

 tannin, before the interior ftrata are materially a6ted upon, 

 thereby prevent the latter in fome degree from imbibing 

 the full aftion of the folution. This renders the texture of 

 the leather lefs equable, makes it harlh and brittle, liable to 

 crack, and of courfe lefs durable. 



Sir Humphrey thinks it probable that another fubftance, 

 befides tannin, combines with the Ikin, namely, tlie cxtratl, 

 to which it owes much of its fupplenefs and tenacity — that 

 the leather gets more of this fubftance from weak infufions 

 of bark, than from the ftrong ones recommended by Seguin 

 — that it is equally infoluble in water — and that, upon the 

 whole, the methods now generally in ufe, may, with a few 

 alterations, be confidered the beft. 



The various difcoveries pretended to have been made, and 

 the numerous patents obtained for their ufe and application, 

 have hitherto tended very little to the advancement of fcience 

 or the progrefs of the art. This may fairly be infen-ed from 

 the conclufion of the celebrated chemiil above-mentioned. 

 Indeed it appears by the fpecifications annexed to the pa- 

 tents, that moft of thefe projefted improvements purport 

 to be either for the different conftrudlion and arrangement 

 of the various pits — for the application of mechanical appa- 

 ratus to dimini(h labour — or for extrafting the tannin and 

 warming t!ie infufion by artificial heat, with a view to acce- 

 lerate the procefs. Thefe fancied improvements are only 

 the idle theories and vifionary projefts of fpeculative minds : 

 but as it may afford information to the curious, and furnilh 

 hints for future difcovery, we fubjoin 



■^ ^jft °J Patents for Tanning. 



'1790, Anthony Fay, efq. of London, for a mechanical 

 apparatus to dimmifti the labour of handling, to grind the 



bark veiy fmall, and to concentrate it, by boiling, into a 

 ftrong extraft. 



1794. Samuel Afliton of Sheffield, for tanning ludes 

 and (kins with certain mineral produftions. As fuch mate- 

 rials were prohibited by the ftatute of James I. an aft of 

 parliament was paifcd to legalize the ufe of them. 



1795. Mr. Tucker of Wickham, Hants, for triple pits 

 compofed of wood, metal, and bricks, to keep up a con- 

 ftant fire at the bottom, to warm the infufion and expedite 

 the procefs. 



1796. William Defmond, efq. of London, for a new 

 mode of tanning, according to M. Seguin's metliod, as be- 

 fore ftated. 



1797. Robert Crofs of Lancafter, for pits on a new 

 conftruftion, to enable him to apply artificial heat and to 

 tan quickly. 



1799. Francis Brewin, efq. of London, for a peculiar 

 conftruftion and arrangement of pits, and for the ufe of 

 machinery, &c. 



1802. John Lawrence, for the ufe of oak faw-duft in 

 tanning. 



1802. Thomas Martin of London, for conftrufting pits 

 on a nev.' plan, &c. 



1 802. John Cant and John Miller of Montrofe, for boil- 

 trig the bark, &c. fo as to extraft the tanning principle more 

 effedlually. 



1807. Robert John Stanley of Lincoln/hire, for tanning 

 light leather without bark, for a peculiar preparation pre- 

 vious to the application of ooze, and for boiling the mate- 

 rials of tanning. 



18 1 3. Sparks Moline, for the ufe of the folid extratl 

 of bark. 



18 15. Thomas Afhmore, efq. for the ufe of all kinds 

 of loot, whether from coal, wood, peat, or bones, and the 

 oils and erapyreumatic liquors arifing from them by diftilla- 

 tion or combuftion, to be applied to the purpofes of tan- 

 ning. . 



Of the utility of the laft-named patent, we fliall give no 

 opinion at prefent ; but of the remainder it may be affirmed 

 that none of the methods therein recommended iiave ever 

 been much praftifed : fome of them which were adopted by 

 a few individuals, were attended with confiderable lofs ; and 

 as moft of them are now laid afide, we may reafonably con- 

 clude that they have not proved beneficial to the projeftors 

 or to the public. 



Before we defcribe the prefent method, it may be ne- 

 ceffary to premife, that in different parts of the kingdom, 

 the faine terms and denominations are fometimes employed 

 to defignate diftinft kinds of leather : but all tanned leather 

 is technically claffed and univerfally known under two gene- 

 ral denominations ; namely, /jid^-s and jhns. The former 

 term being commonly applied to the larger animals, as bulls, 

 oxen, cows. Sic. which are chiefly intended for the foles of 

 itout ftioes, and other purpofes requiring very thick and 

 folid leather ; while tlie latter term is ufed for calves, 

 feals, &c. which, being thinner and more flexible, are in- 

 tended for the upper leathers of flioes and boots, for faddles, 

 harnefs, &c. 



The heavieft and ftouteft of the bull and ox hides are 

 generally feleAed to make what are technically called iiitts 

 or l/rtcis, and are manufa£tured in the following manner. 



When the horns, &c. have been removed, the raw hides 

 are laid on a heap for two or tliree days, and are then fuf- 

 pended^ on poles in a clofe room, called a fmoke-houfe, 

 which is heated fomewhat above the common temperature 

 by a fmouldering fire : this occafions incipient putrefadlion, 



which 



