35 



THE POPULAR SCIENCE MONTHLY. 



converting it into an almost perfect vacuum, and at the same 

 time force liquor into it, producing a pressure of one hundred 

 pounds to the square inch. Between the hides he placed cocoa 

 matting, so that the free circulation of the liquor should be in no 

 way interfered with. In the top of the tank, where it was impos- 

 sible to put hides, some small blocks of wood were placed. He 

 afterward exhausted the air in his tank, forced in the liquor, and 

 then waited several days, but his experiment was a complete 

 failure. On examining the contents of the tank, he found the 

 wood thoroughly saturated with tannin, but the hides were 

 scarcely colored. The pressure that would kyanize wood would 

 not tan leather. Recently attempts have been made to employ 



Fig. 10. Scouring Machine. 



electricity to hasten the operation, but as yet no practical and 

 satisfactory " quick tanning " process has been found. 



Few, if any, of the pioneer tanneries remain. That, however, 

 which used to belong to Mathias Ogden and Colonel Oliver 

 Spencer, at Elizabethtown, N. J., in 178-4, was probably a good 

 example of the original type. That consisted only of forty or 

 fifty oblong boxes, without cover or outlet below, sunk into a 

 bed of clay near a small stream. The boxes did duty as vats 

 and leaches. On one side of them stood an open shed which 

 fronted a half-dozen more boxes, the " limes " and " pools " of the 

 beam-house, while on the other side was a circular trough, made 

 of hewed timber, fifteen feet in diameter, in which the bark was 

 crushed by alternate wooden and stone wheels propelled by two old 

 horses. It was essentially a home-made plant. The wind swept 

 through it without hindrance, and the rain and snow beat un- 



