WOOD-PULP. 161 



cheaper than pulp made from rags, but takes impressions better, 

 and wears out type less. On the other hand, paper made of 

 wood-pulp soon becomes brittle and turns yellow, so that there 

 is a danger that it may be torn, after ten years or so, and it is 

 therefore useless for important documents. Pure wood-paper 

 can therefore be used only for pasteboard, packing -paper, and 

 the coarser kinds of printing-paper. The better and finer kinds 

 of paper require a certain admixture of rag-pulp or esparto 

 grass, although wood-pulp has, to a large extent, taken the 

 place of the latter. 



At first, aspen and lime-wood were preferred for making paper 

 pulp, but as the supply of these woods was quite insufficient for 

 the demand, coniferous wood was tried, and spruce soon came 

 into the first rank for the purpose. Besides the above woods, 

 those of poplars, beech, and birch are also used. The assort- 

 ments most in demand are poles and stems (converted into billets, 

 as for firewood), of 4 inches to 1 foot in diameter, dimensions 

 which are always available from the inferior classes of timber. 

 More recently timber of even larger dimensions is in demand, 

 as its cost of transport, &c., is less. At the same time, 

 sound timber, free from knots and branches, is required, and 

 dead or half-dead material from thinnings is rejected. The 

 wood intended for paper-factories is now usually converted in 

 the forest into barked blocks about 6 feet (2 meters) long and 

 4 to 8 inches in diameter, which are stacked like cord-wood. 



The enormous demand which has arisen for paper-pulp has 

 been one of the chief causes of the destruction of large areas of 

 private forests, for even moderate-sized poles can be thus 

 utilized. In North America, during the three years ending in 

 1894, 200,000 acres of forest have been denuded to satisfy the 

 demands of 210 paper factories. 



[This industry has the advantage of iitilizing mxich wood from 

 thinnings, whicli might otherwise be wasted. — Tr.] 



Paper-pulp is now-a-days prepared in various ways, among 

 which the mechanical and chemical methods are those chiefly 

 followed. These two methods give very different results as 

 regards paper-manufacture, the product of the mechanical 

 method, termed paper-pulp, being more granular, whilst that of 

 the chemical method, termed cellulose, is more fibrous, and 



VOL. V. M 



