356 JOURNAI, OF FORESTRY 



"the solution of the wood-waste problem appears to lie mainly along 

 chemical lines, so that in connection with the industries already utiliz- 

 ing wood by chemical means a systematic survey of several typical 

 American woods seemed essential." 



In discussing the general composition of wood, Schorger seems to 

 accept the view that lignocellulose consists of cellulose chemically com- 

 bined with lignin, and doubts the assumption made by Konig and Rump 

 (Chemie und Struktur der Pflanzen-Zellmembran, Berlin, 1914), who 

 determined by experiment that the natural cell membranes consist of 

 cutin, cellulose, and lignin in simple physical combination. As cellulose 

 obtained from wood exhibits somewhat different reactions than cellu- 

 lose from cotton, there has been some discussion concerning the proper 

 structural formula which can be applied to wood cellulose. The differ- 

 ence is explained by Cross and Bevan by assigning to the wood cellulose 

 an oxycellulose structure, though this explanation has been rejected by 

 other investigators. 



According to Schorger, the principal hemi-cellulose in wood are 

 pentosans, (CgH804)n, though small amounts of hexosans, (CeHioOg)^, 

 such as mannan and galactan, are frequently present. Hemi-celluloses 

 are insoluble in water, but are soluble in dilute acids and alkalies and 

 are more easily hydrolized by dilute acids than the true cellulose. 



In a discussion of the methods of drying wood, the effect of heat upon 

 the chemical structure of wood is given consideration. It is stated that 

 Ost and Westhoff (Chem.-Ziet., 33 (1909), p. 197) beheve that a tem- 

 perature of 120° to 125° C. is necessary to expel all hygroscopic mois- 

 ture, but that it is very doubtful if water retained near this temperature 

 should be considered as merely hygroscopic. Schorger accepts the view 

 that all hygroscopic moisture can be removed by heating at 105° to 107° 

 C, and this method was employed as the standard of absolute dryness, 

 as all of the analyses were necessarily based upon the dry weight of the 

 wood. Prolonged heating at this lower temperature caused no loss in 

 weight that could be ascribed to chemical changes in the structure of 

 the wood, which is not in accord with the results obtained by other 

 investigators. 



In determining the volatile oil, it was found that the method of sub- 

 tracting the amount of moisture found by the xylol method from the 

 total loss in weight obtained by drying in an oven at 105° to 107° C. 

 gives lower results than if the volatile oil is expelled by steam. The 

 only reliable method of determining the waxes, fats, and resins was 

 found to consist in extracting the wood with ether and weighing the 

 extract after the evaporation of the ether. The action of alkali on 



