DISTILLATION OF WOOD. 107 



Wood Pulp and Distillation Products. One of the most 

 important industries connected with forests is their use for paper 

 pulp. For this purpose all kinds of wood may be used, but on 

 account of its superior quality and the ease of working little is 

 used in this country at present besides Spruce. Many experi- 

 ments have been made with Poplar, and it also is used to some 

 extent, but Spruce is very much preferred on account of its bet- 

 ter fiber. Paper pulp is made in two ways: First, chemical; 

 second, mechanical. Chemical pulp is made by treating the tis- 

 sues of the wood with chemicals which dissolve out the lignin 

 substances until only the cellulose or pulp is left. There are sev- 

 eral processes used, one of which is by boiling the wood in Glau- 

 ber salts for seven hours, after which the pulp is washed clean 

 and bleached with chloride of lime until quite white. This 

 process is more expensive than the sulphite process, in which sul- 

 phurous acid is used, but is said to give a better product. All 

 kinds of wood may be converted into chemical pulp, but very 

 dark colored and very resinous kinds are usually avoided. Ordi- 

 nary paper pulp is made by grinding Spruce wood on large 

 stones, against which it is pressed by hydraulic power. For the 

 manufacture of very tough paper and of leather board it is cus- 

 tomary to boil the wood a long time before it is ground. Wood 

 that is cooked a long time before grinding makes a dark colored 

 but very tough product. In the manufacture of ordinary print- 

 ing paper the wood is put at once upon the stone, and the pulp 

 from it is rolled into paper. It is customary to mix a certain per 

 cent of chemically prepared paper pulp with ordinary wood pulp 

 in order to improve its strength. Wood pulp is not only manu- 

 factured into paper, but boards, buckets, car wheels, and a thou- 

 sand other things, are made from it. Its use is almost unlimited. 



By the Destructive Distillation of Wood (all kinds of 

 wood, all sizes, logs, refuse, sawdust) we obtain charcoal, vine- 

 gar, alcohol, creosote, gas, tar; pyroligeneous, oxalic, acetic and 

 other acids; acetone, paraffin, naphthalin; lampblack and other 

 products. From the bark of Oak, Hemlock, Chestnut and other 

 trees the tannic acid used in tanning leather is obtained. 



As we have digressed slightly by including bark under the 

 term "wood," we may go farther, and take in also the sap from 

 which is obtained turpentine, resin, gums and rubber, sugar, 

 liquors, medicines; the pith, which gives us food and fiber for 



