WOOD PULP AND PAPER 45 



in the paper mill. Laps made up in this way contain about 60 per cent of 

 water. 



Drying. 



In the manufacture of dry pulp the pulp passes from the screens into a 

 box containing a revolving cylindrical screen and is picked up and carried 

 on a felt the same as in the case of the lap machine. In this case, how- 

 ever, it is carried through a series of three sets of press rolls which press 

 the water out of the sheet of pulp. This sheet is then carried over a set 

 of about 36 hot cylindrical drums which are arranged very similarly 

 to those of a paper machine. These drums are heated by steam and are 

 kept at a temperature of about 250 F. As the dry pulp comes off the 

 rolls it is wound on a reel at the end of the machine. There are two of 

 these reels and while one is winding up the pulp that on the other is re- 

 wound and run through a set of knives and re-wound in rolls 2 ft. long 

 and weighing about 200 Ib. These rolls are then tied, and loaded into the 

 car for shipment. 



Dry pulp is never made in a mill where the pulp is going directly into 

 paper as it is unnecessary to drive off all of this water. Dry pulp is made 

 for long shipment and long storage. 



Power. 



Power in a pulp mill is not restricted to any one type. In many 

 places water power is used entirely. Steam is also used and electricity is 

 used where it can be manufactured cheaply. 



A loo-ton mill requires about 1500 h.p. to operate it. 



Cost of Production. 



The cost of manufacture of pulp varies in different mills but a good 

 average before the war would be about $35.00 a ton, unbleached. The 

 process of bleaching added about $12.00 to this initial cost. 



Spruce and hemlock, in the summer, are practically alike and sell at 

 the same price, but in winter they vary greatly, both in quality and sale 

 price. 



At a large pulp mill in New York the following costs were determined 

 over a period of several months in 1916: 



