418 JOURNAL OF FORESTRY 



likely to warp. Soft woods contain much spring wood. They are 

 dark colored and coarse grained and do not take polish well. They 

 crack and split easily. Oaks growing in high forest on rocky soil 

 produce soft, easily worked wood. 



Chemical Composition. — The chemical composition of freshly cut 

 wood with the bark still on averages as follows : hygroscopic moisture, 

 40 per cent; ash. 1 per cent; elemental constituents, 59 per cent. The 

 amount of water contained in wood varies with the different species 

 and with the time of felling. It also varies in different parts of the 

 tree. In winter wood contains at least 10 per cent of moisture. Young 

 wood contains the greatest amount ; then the branches, and lastly the 

 trunks, which contain the least. 



Wood is composed chemically of cellulose and vasculose. Simple 

 cellulose (CioHjoOio^t is soluble in Schweizer's liquid. Vasculose 

 (CigHj^Ojo) is more abundant in heartwood than in sapwood, and in 

 hard woods than in soft and resinous woods. This is the incrustation 

 substance of wood. In distillation it furnishes the greater part of the 

 acetic acid and the pyroligneous acid; This substance decomposes 

 under the action of atmospheric oxygen and nitric acid, causing wood 

 to deteriorate when exposed to air. 



Vegetable tissues contain soluble ferments or diastase. Among these 

 are ; amylose, which changes starch to dextrine ; pectose, which changes 

 pectin to pectic acid ; pepsin (in the latex of the fig and the juice of the 

 pawpaw) ; emulsin (in the almond, bay cherry, sorbus) ; saponin, which 

 changes oil to glycerine and fatty acids. 



Other substances found in plants are ; starches, the reserve stuff on 

 which young shoots live ; organic alkalies, as quinine, caffeine, theo- 

 bromine; reserve matter, abundant in certain palms and producing 

 starch sediment ; gums, as in acacia ; fatty substances, as the oil con- 

 tained in olive, palm and nuts ; glue, produced by a reserve substance 

 called viscine, as found in holly bark and in the mistletoe berry ; cam- 

 phor, in Dryobalanops and Cinnamorum camphora ; and sugars, for 

 instance, glucose, saccharines, mannites (ash, maple), pinites (pines), 

 quercites (oaks). These sugars are produced by the conversion of 

 starch into dextrine, then into glucose ; they are abundant in the sap 

 of the American Negundo aceroides. There are also the melitose of 

 the eucalypts, the melezitose (galactan?) of the larches, the dulcite of 

 the spindle tree, and the sorbite of the Sorbus species. Ligneous tissues 

 also contain glucosides, such as salicin, in willow ; betulin, in birch, 



