470 Jori.'.VAL OF Ft)kKSTRV , 



extract only one uniform substance from wood. According to their 

 resistance to various reagents, the non-celkilose constituents of wood 

 are assigned to five or six groups of substances. The various investi- 

 gators are apparently coming to the conclusion that the basal compo- 

 nents of each substance are held together by physical (surface tension) 

 rather than by chemical forces. 



In the estimation of the cellulose content of wood by the Cross and 

 Bevan chlorination method, the wood sample should be reduced to 

 "sawdust" by rasping with a wood rasp until a sawdust is obtained that 

 will pass an 8o-mesh sieve, but which will be retained on a lOO-mesh 

 sieve. It is stated that "since Schorger (Jour. Ind. & Eng. Chem., June, 

 1917, pp. 556-566) found that the final cellulose still contained frag- 

 ments of wood that had been only partially reduced, and therefore gave 

 a strong methoxy reaction, it is not surprising that his values for cellu- 

 lose were extremely high, and that great variations in the results were 

 experienced.^ Johnson and Hovey, writers of the article under review, 

 are unable to agree with Schorger when he says that "in obtaining 

 cellulose absolutely free from lignin the error involved by the destruc- 

 tion of the cellulose is out of all proportion to that caused by the pres- 

 ence of small quantities of lignin." 



The writers propose a modification of the chlorination method in the 

 estimation of cellulose, which is featured by a preliminary digestion 

 with acetic acid and glycerine, thus hydrolizing the lower carbohydrates 

 and furfural-yielding substances before the wood is chlorinated . The 

 new method indicates a lower percentage of cellulose, aspen (Popuhis 

 trcmuloidcs) yielding 57.25 per cent, as compared with 60.95 P^r cent 

 bv the old method; red spruce (Picea ruhens), 50.64 per cent (new) 

 and 54.58 per cent (old), and balsam fir {Abies balsamca), 51.60 per 

 cent (new) and 54.43 percent (old). 



In view of previous experiments (Pulp and Paper Mag. of Can., Vol. 

 XV, 1917. p. 333). the variation in the cellulose content of a disc of 

 balsam fir, as determined by Johnson and Hovey, is interesting. The 

 cellulose content of the wood varied from 51.2 per cent in a sample 

 taken in the sapwood to 54.15 per cent in a sample taken in the region 

 adjacent to the pith, while the intermediate wood yielded 53.28 per 

 cent. Sapwood of aspen yielded 51.24 per cent and heartwood 59.88 

 per cent. Rotholz in a disc of balsam fir yielded 39.42 per cent, wide- 

 ringed wood from the same specimen 50.35 per cent, and narrow-ringed 

 wood 52.85 per cent. 



* Schorger obtained his samples with a specially arranged saw or by scraping 

 the wood with a cabinet-maker's scraper and shredding the shavings. Material 

 that passed through a 40-mesh seive was considered satisfactory. 



