36 



FOREST PRODUCTS 



After screening, the pulp is treated in a wet press or lap-machine in 

 order to remove the large quantities of water and leave a pulp suitable for 

 shipment to the paper mill. The watery mixture is pumped contin- 

 uously into a large receiving reservoir or vat in which a hollow drum 

 rotates. The surface of this drum is made of fine wire gauze. The 

 pulp in solution is caught by this fine gauze and adheres to it while the 

 water passes through the gauze and out through the waste pipe. 



This thin layer of pulp is carried by the rotating drum up above the 

 surface of the liquid in the vat and is picked off by a traveling felt which 



Photograph by A. M. Richards. 



FIG. 4. Grinder room in a large pulp mill containing 24 wood grinders of the three-pocket 

 type. The grindstones are 60 in. in diameter and have a a8-in. face or grinding surface. 

 Pressure of wood is maintained against the stones at a rate of 70 Ib. per square inch. 

 Capacity of grinding room is 180 cords per day of twenty-four hours. 



passes over a roller and which comes into contact with the drum. The 

 thin sheet of extracted pulp passes first between small rollers which press 

 out most of the remaining water. From these rollers the sheet of pulp 

 is wound up in a continuous sheet or roll on a large wooden drum until it 

 is sufficiently thick to peel off. At various intervals, the operator cuts 

 across this sheet with a wooden stick, removes the layers of pulp and folds 

 them into convenient sizes for piling or for shipment or baling. When 

 baled, it is commonly submitted to hydraulic pressure to remove all the 



