222 On the E.iyort and Cun&umption, dc. 



trating the cells and depositing its tannin, must be displaced 

 by another and stronger infusion. As the outside cells also 

 are the first to attract the tannin, they consequently form a 

 barrier to the inner ones, which complete and long saturation 

 alone overcomes. If a hide be taken from the pit before it 

 is completely tanned and cut through, a white streak in the 

 centre will mark the line of cells beyond wliich the tannin 

 has failed to penetrate. 



The great desideratum, therefore, is, a means of forcing a 

 continuous stream of extract through the hide without 

 destroying or injuring the texture. A variety of plans have 

 been tried to effect tins, — some with partial success, others 

 with complete failure ; a few will be found mentioned in 

 the article already alluded to, and by the saving of time 

 effected with some of them considerable profits have been 

 made : but there is generally some defect, — the hide is either 

 too much stretched, imperfectly tanned at the edges, or 

 marked by the apparatus used. The rolling between 

 cylinders after emersion seems, however, to have obviated all 

 these ; and no doubt this discovery will be improved upon. 



It was thought that by placing hides in a strong chamber 

 from which the air could be exhausted, and sudden injections 

 of extract made, that the water might be drawn from 

 the hides in this way after each injection, and the process 

 repeated any number of times required ; but if this plan 

 were tried, capillary attraction alone would prevent its 

 success. Many have succeded in tanning a single hide 

 quickly ; but any invention, to be of value, must be capable of 

 being applied to hundreds at a time before it can compete with 

 the present mode, — by which, in some of the large tanneries, 

 thousands are turned from the pits at once. 



It is singular that an art known from the earliest ages 

 should have remained until the present day without any 

 material improvement. Were Simon, the tanner, to appear 



