DISTILLATION OF WOOD. 167 
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; lampbjack 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 
