hanging them in the air; then the tan is cleared off them, and they 

 are put into a place neither too dry nor too moist; they are there 

 well stretched over one another with weights a-top, to keep them 

 tight and strait; and so this condition are sold under the denomina- 

 tion of bend-leather. This is the method of tanning bullocks or 

 oxen-hicies. Cows, calves, and horses skins are tanned much after 

 the same manner of those of oxen, except that they are only kept 

 four months in the lime pit, and that before they be put in the tan, 

 there is a preparation required thus: cold water is poured into a 

 wooden vat, or tub, wherein the skins are put, which are kept 

 stirring while some other water is warming in a kettle; and as soon 

 as that water is little more than luke-warm, it is poured gently into 

 the vat, and upon this is cast a basket of tan; during which time 

 the skins are still kept turning, that the water and tan may not 

 scorch them. After an hour they are taken out and cast for a day 

 into cold water, then returned to the former vat and the same water 

 they had been in before, and here they are left for eight days: 

 which expired, they are put into the tan-pit, and three coverings of 

 tan given them; the first of which lasts five weeks, the second six, 

 and the third two months. The rest of the process is the same in 

 all respects as that delivered above. 



The Process of Tanning in i 8 i 3 



(From Thomas Martin, The Circle of the Mechanical Arts, pp. 542-546.) 



TAN, tannin, or the principle that effects the operation of the 

 art of tanning, is usually produced from the bark of oak, chopped 

 and ground in a mill into a coarse powder. M. Deyeux was the 

 first chemist who ascertained and gave an account of the peculiar 

 nature of tan. He pointed it out in his analysis of nut-galls, as a 

 peculiar resinous substance, but without assigning to it a name. 

 Seguin, who ranks high in France, as a chemist, and as one who 

 has entered deeply into the principles of tanning, though not so 

 much regarded by the tanners in England, engaged in a very exten- 

 sive set of experiments on the art of tanning leather, during which 

 he discovered that tan has the property of precipitating glue from 

 its solutions in water, and also of combining with skins of animals. 

 This led him to suppose it the essential constituent of the liquids 

 employed for the purpose of tanning leather, and hence arose the 



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