306 . PHILOSOPHICAL TRANSACTIONS. [aNNO 1778. 



hide) the manufacture is finished, so far as relates to tanning, since nothing now 

 remains but to dry the goods thoroughly, by hanging them up in airy lofts built 

 for the purpose. Such in general is the process for tanning calf-skins, and those 

 lighter sorts of hides called huts; but the large, thick, heavy hides, of which 

 the strongest and most durable kind of sole-leather is made, require to have their 

 pores more thoroughly opened before the ooze can sufficiently penetrate them. 

 For this purpose, while the hides are in the putrescent state, from being allowed 

 to heat i'l the manner already mentioned, and well soaked in an alkaline ley, they 

 are thrown into a sour liquor, generally brewed from rye, that the effervescence 

 which necessarily ensues may open the pores. The tanners term this operation 

 raising, as the leather is considerably swelled, in consequence of the conflict be- 

 tween the acid and alcali. This is an English invention: for it appears from M. 

 de la Lande, who was employed by the Royal Academy of Sciences to write on 

 the art of tanning, that the foreign tanners know nothing of this branch of the 

 business: indeed, their whole process, according to his account, is slovenly, and 

 even more tedious than our common method, and must make but very indifferent 

 leather. 



When the raising is accomplished, the leather is put into the handlers, and 

 worked in them for the requisite time ; then laid away in the vats, and there left 

 to macerate till the tanning is found to be completely finished; which, for the 

 heaviest kind of leather, such as this now spoken of, requires from first to last 

 full 1 years. At least, the tanners of this country cannot make sole-leather in 

 less time; what they are able to perform in England, I am not so thoroughly ac- 

 quainted with. It is this tediousness of the process which enhances the value of 

 leather; and the returns being so slow, the trade of tanning never can be carried 

 on to advantage, but by persons possessed of a large capital ; therefore, one sure 

 way of increasing the number of tanners, and of course of bringing down the 

 price of their manufacture, is to shorten the process; and if at the same time we 

 can improve the quality of the leather, and save somewhat in the expence of 

 tanning materials, the public will be essentially benefiterl in respect to one of the 

 necessary articles of life. 



Now all this can be done by pursuing the method laid down in the inclosed 

 paper, and which may be introduced into any common tan-yard. With respect 

 to time, it is possible, in the way that I have found out, to finish leather in a 

 4th part of what is required in the ordinary process; for I have repeatedly had 

 calf-skins tanned in 2 or 4 weeks, which in the common way could not be done 

 in less than as many months. I shall not pretend however to afhrm, that the 

 business can be carried on in the large way with such expedition; because a great 

 deal of this abridgment of time was probably owing to frequent handling and 

 working of the leather; but I am confident, and know it from 4 years experience, 



