PINACE.E 359 



and late (summer) wood well marked. The medullary rays are 

 numerous but fine. Heartwood and sapwood are well defined, 

 particularly in the species known as " hard pines," where the 

 heartwood is much darker than the sapwood. In the " soft " 

 or " white pines " the dividing line is also well defined, although 

 the colour is paler and more uniform. Newly worked wood has a 

 resinous odour which varies in intensity according to species. It 

 is very inflammable, so much so that wood of some species has 

 been used for torches. 



Many of the pines yield timber of vast economic importance 

 which is used for innumerable purposes, including the construction 

 of bridges and viaducts, house-building, railway sleepers, and 

 street paving blocks, furniture, pattern-making, toys, carving, 

 box-boards, paper pulp, etc. When used in contact with the 

 ground, however, the wood should be treated with creosote or 

 some other preservative. 



Several species yield (by tapping) an oleo-resin which by dis- 

 tillation furnishes turpentine and rosin. The wood is subjected 

 to distillation by two distinct methods, destructive or dry dis- 

 tillation, and steam distillation. By the former method the wood 

 is calcined in retorts in the absence of air. As the various gases 

 or vapours are given off they pass by special openings into a 

 copper condenser. The crude distillate is then refined and yields 

 light and heavy tar oils, turpentine, pitch, pyroUgneous acid, etc. 

 The residue of the wood is withdrawn as charcoal. A smoke 

 deposit furnishes lampblack, and various gases are available for 

 fuel. Roots and waste wood can be profitably dealt with by this 

 means. An average cord of wood (128 cubic ft.) of P. palustris, 

 in the United States, yields 7 gallons of turpentine, 2 gallons of 

 pine oil, 32 gallons of tar oOs, 41 gallons of tar and pitch, and 39 

 bushels of charcoal.^ In steam distillation the wood is reduced 

 to small chips before placing in the retort ; it is then treated with 

 steam for several hours, which removes most of the turpentine 

 and oils. The steam and oil are then passed into a condenser and 

 thence into a separator. After various processes, turpentine, pine 

 oil, and rosin are obtained. An improvement on the steam ex- 

 traction of these products is the use of a solvent such as naphtha, 

 benzol, gasohne, etc.^ Pine-leaf oil is procured by distillation of 

 the leaves of certain species. This is chiefly used for medicinal 

 purposes. The leaves are sometimes reduced to fibre which is 

 used for weaving into medicated underclothing, for the manufac- 

 ture of coarse matting resembling coco-nut matting, for surgical 

 dressings, and for stuffing upholstery, mattresses, etc.^ The 



1 Brown, Nelson Courtlandt, Forest Prods., their Manuf. and Use, 229 (1919). 

 aLoc. cit. 231. 



' Pine-needle Fibre. Dipl. and Cons. Rep., Ann. Ser. (State of Oregon), Nos. 

 2,570, p. 9, and 2,666, p. 23 (1900). 



