FOREST UTILIZATION 97 



endless belts of cloth which carry it as a thin 

 matting through a series of heated rolls, 

 (f) The mattings are dried by superheated steam, by 

 pressure or in the air. Pulp is shipped in rolls 

 about 3 feet long and iJ/2 feet in diameter. It is 

 not paper but merely the leading raw material 

 for ordinary paper. 

 II. Soda process. 



This process consists of : 



(a) Sawing wood into discs about I inch thick. 



(b) Grinding and dissecting the discs into fragments 



about 1/24 inch by i inch in size. 



(c) Packing the material into perforated iron boxes 

 which are placed in digestors containing a solu- 

 tion of caustic soda. 



(d) Boiling the wood for four hours under a pressure 



of 125 pounds. 



(e) Grinding between stones. 



(f) Repeated washing and sifting. 



(g) Bleaching with chlorate of lime and washing, 

 (h) Taking up mass by endless rolls of cloth and dry- 



"ing it between heated rollers, 

 (i) Reclaiming caustic soda by boiling and melting. 



III. Sulphite process. 



Same as the soda process, excepting points "c," "d" 



and "g." 

 The wood fibre is first cooked without chemicals and 



then boiled for 60 hours with calcium sulphite a cheap 



chemical usually prepared at the mill itself. 

 No or only little bleaching is required, the fibre being 



free from color when leaving the digestor. 

 The expense of manufacture per ton of sulphite fibre is 



said to be as follows : 



Two tons of spruce $ 9.00 



Coal 3-00 



Sulphur 3.30 



Lime 7 



Labor inclusive of office force 7.00 



Wear and tear 2.50 



Total $25.50 



These figures may seem to be unusually high. 



The sulphite process offers the following advantages : 



(a) It is cheaper (no bleaching, cheap chemicals). 



(b) It does not interfere with the strength of the fibre. 



(c) It yields a larger output of fibre per cord. 

 Hence the sulphite -process is rapidly superseding 



the soda process. Exception in poplar. 



