THE WOOD 237 



12. Wood is ground into pulp and made into paper 

 and pulp boards with endless variety of application. 

 Wood pulp, made by chemical processes, results in cellu- 

 lose and its countless derivatives, which are capable of 

 supplying almost anything, from a shirt collar to a car 

 wheel. 



13. Distillation of wood furnishes charcoal to the smithy 

 or furnace ; vinegar to the table ; alcohol to the artisan ; 

 creosote to the wood preserver ; gas for fuel and light ; 

 tar for roof boards ; pyroligneous, oxalic, acetic, and other 

 acids, as well as acetone, paraffin, naphthalin, etc., to the 

 manufacturing chemist ; and, Ijy a slight variation of the 

 process, lampblack to the printer and painter. 



Wood also differs from the metals in several other 

 respects. It is not fusible ; it cannot be cast ; hence, to 

 duplicate a form in wood requires the same amount of 

 effort as did the original. Changed into pulp, and still 

 more into cellulose, this drawback is largely overcome. 

 Wood cannot be welded, — though, as stated before, this 

 is more than compensated by gluing ; nevertheless, an 

 end-to-end junction of the kind produced in iron cannot 

 be effected. 



Wood cannot be rolled; it nuist bo cut into shape; but 

 owing to its softness and cleavability this requires incompar- 

 ably less effort and equipment than the rolling of metals. 



Wood is hygroscopic ; it contains water under all ordi- 

 nary conditions, and the amount so contained vai'ies with 



