CLAY -WORKING INDUSTRIES. 99 



The agitator is the counterpart of the blunger, except as to size and 

 strength of its driving mechanism. It generally is made big enough to 

 hold four blungers of slip and its function is to keep this slip in suspension 

 to prevent the settling of clay. 



The next machine is the pressure pump, which is used to take the slip 

 from the agitator and put it into the filtering press against whatever head 

 of pressure may exist there. There is nothing peculiar about this pump 

 except that it must be strong and ought to be provided with extra facili- 

 ties for packing, etc. Some are arranged to work in oil and impart their 

 alternate suction and pressure to the slip without coming in contact with 

 it. The latest and best devise for effecting this purpose is a compressed 

 air plant made purpose^ to work up to a pressure of one hundred and 

 twenty-five to one hundred and fifty pounds. The slip is run into a strong 

 tank by gravity, and is forced out again by air pressure into the press. 

 This absolutely does away with the constant wear and tear of the pump. 

 Only a factory of large size can afford to use this plan, as the cost of put- 

 ting it in operation is rather heavy. 



The press or filter is the most ingenious and most troublesome part 

 of the washing machinery. It consists of a series of iron or wooden frames 

 suspended on iron side bars. These frames are covered with single or 

 double layers of stout canvas or duck, made for the purpose. Through 

 the center of each frame is a hole also lined with duck. When a press is 

 in order, ready to fill, these frames or chambers are squeezed up tight 

 against each other by a powerful screw at one end of the press. The can- 

 vas between the edges of the iron frames makes a tight gasket or joint 

 and the holes in the center coincide all the way through, so that between 

 the canvas of each two frames, there exists a duck-lined cavity, commun- 

 icating by the central hole with the similar chambers on either side of it. 

 When the slip is pumped in, it fills these cavities and the water soaks out 

 through the canvas and drains away, leaving the clay behind. When the 

 cavities are filled and no more slip can be pumped in at a pressure of one 

 hundred and twent} T -five pounds to the inch, the operation is complete. 

 The screw is loosened, the frame separated and the clay is disengaged in 

 flat leaves or plates one to two inches thick and weighing thirty-six to 

 forty pounds each in the ordinary sizes. 



The plates of washed and filtered clay are now tempered to the re- 

 quired consistency in a pug mill of vertical design and simple construc- 

 tion. The cost of the various machines for such a plant, will run from 

 $1,000.00 to $1,500.00, according to details, without the power. 



Washing plants are constructed by several machine shops in the 

 state. The following make a specialty of this business: M. Patterson & 

 Co., E. Liverpool; H. J. Boyce, E. Liverpool; The Bonnot Co., Canton. 

 The Griffith & Wedge Co., Zanesville, and the South Zanesville 

 Machine Co. 



