268 THE UTILISATION OF WOODLAND PRODUCE. 



II. Wood without resin-ducts. 



1. Heartwood about same colour as sap wood, pale-yellowish or reddish- 



white ("White Pine"); only recognisable from Spruce by not 

 having resin-ducts ...... SILVER FIR. 



2. Heartwood distinctly darker than sapwood ; annual rings very clearly 



marked by a narrow line of compact Autumn wood (CYPRESSES). 



(1) Sapwood yellowish- white and narrow ; heartwood pale brown 



(Thuja gigantea) RED CEDAR. 



(2) Sapwood whitish ; heartwood light pinkish-red or brownish- 



red (C. macrocarpa) . . MONTEREY CYPRESS. 



(3) Sapwood yellowish ; heartwood pale yellowish - brown (C. 



Lawsoniana) LAWSON'S CYPRESS. 



II. As regards Chemical Composition, green wood consists 

 usually of about 50 to 75 per cent of woody substance, and 

 25 to 50 per cent of sap or water containing organic and 

 mineral substances in solution and suspension ; and even after 

 being seasoned or air-dried, from 10 to 12 per cent of the 

 weight of wood consists of water. The framework of the 

 woody fibres, vessels, and cells is cellulose (C 6 H 10 5 ), with a 

 composition of about 44 carbon, 6 hydrogen, and 50 oxygen 

 per cent, which during a process called lignification loses 

 oxygen and absorbs more carbon along with nitrogen and 

 mineral substances. But the elementary composition of the 

 dry woody substance varies only slightly in different woods, 

 the rough average consisting of the following percentages : 

 50 carbon, 42 oxygen, 6 hydrogen, 1 nitrogen, and 1 ash or 

 incombustible mineral substances, consisting chiefly of lime, 

 potash, magnesia, and phosphoric acid, the amount and com- 

 position of which vary, of course, according to the kind of tree, 

 and the soil, situation, and climate. The organic and the 

 mineral substances in solution or in suspension in the sap are 

 either parts of the cell- wall or products of its transformation, 

 and include protein or nitrogenous matter, carbohydrates, and 

 glucosides ; oils, resins, and aromatic substances ; tannic, oxalic, 

 and other acids ; and dyestuffs ; and these combine to give the 



