19 



elasticity, tlie stnMi<rtli of tlu' material aiitl other i)roi>erti('s wliicli are. exliibited as reaetions to 

 the. intlucncc ot api)lie(l stresses, and those which need consideration in the inccliaiiical use of the 

 material in the various arts. 



Ilaviuji^ investiii'ated the iiiatcrial in its imriiial coinlil ion, uc would necessarily come toacon- 

 sideriition of sucii ])hysieal and chemical conditions of the material as are abnormal and known as 

 disease, decay, or defects. 



Finally, havinj;' deterniiiied the properties and their chanj;cs as exhibited iu material produced 

 iiuder chausiuj;- conditions or ditt'ering in physical and sliiutural respects, it would remain the 

 erowninji' success and yoal of this science to relate mechanical and physical properties with ana- 

 tomical and physiolojiical dcvelojiment of the wood snl)stance. 



The subject-matter (•onii)rised in this I)ranch of apidied natural science, then, may bo brouj;hfc 

 into the followins-- sehcmatie view: 



TIIWBER PHYSICS OR THE SCIENCE OF WOOD. 

 I. — Wood STRt'CTCHE on XYLOTO.MY. 



(a) Exterior Jorm. 



Here, wonlil t)(> doscril)ocI the form (lovolojiineut of timbor in thd standing troo, ditforentiatod into root 

 system, root collar, bole or trunk crown, branches, twigs; relative amounts of material furnished by each, 

 (ft) Inlirior stnictiir<tl apjimrancc; <lifferentiation and arrangement of groups of structur;il elements. 



Here would be described the gross structural features of the wooil, the distril>ution and siz<> of medul- 

 lary rays, vessels, fibro-vascular liuiulles, as exhioited to the naked eye or under the magnifying glass on 

 tangential, radial, and transverse sections; the apjiearance of the annual rings, their size, regularity, dif- 

 ferentiation into summer and spring wo(h1, and all <listiuguislilng features due to the arrangement and 

 proportion of the tissues composing the wood. 



(c) Minute anatomy or hixtolony; diifereutiation and arrangement of structural elements. 



Here the revelations of the microscope are recorded, especi.ally the form, dimensions, and structure of 

 the different kinds of cells, their ariangenient, proportion, and relative importance iu the resulting tissues. 



(d) Compuratire classification of woods, ai'.cordiug to siructurul features. 

 («) Laics of wood firotrtli- with reference to structural results. 



Discussion of the factors that inlluenee thi> formation of wood in the standing tree. 

 (/) Ahnormal formations. 



Burls, bird's-eye, curly, wavy, and other structural abnormities .and their causes. 

 II. — Physical properties, i. e., properties l)ased on molecular (physical) constitution. 

 (a) Exterior appearance. 



Such properties .as can 1)6 observeil through the unaidral senses, as color, gloss, grain, texture, smell, 

 resonance, 

 (ft) Material condition. 



Such properties or changes as are <leteruiined by measurements, as density or Aveight, water c-ontents 

 and their distribution, volume and its changes by shrinkage and swelling, 

 (c) Classification of woods according to pln/sico-tcchnical )i7-operties, i. c, such physical projierties as determine their 

 application in the arts. 

 III. — Chemical PROPERTIES, i. e., projierties based on atoniii; (chemical) constitution. 

 (a) General chemical analysia of irond ((|nalitati\T ;ind i|uantitatlve). 



Here would be discussed tlie eliemical constitution of tlitferent woods mui! ditfereut p.'irts of trees and 

 its changes due to pliyslologica! |>rocesses, age, conditions of growth, eti'. 

 (ft) f'arholiydralcs of the wood. 



Here would be more specially discus.sed eeilulo.se and ligiiin. emli tiii niaticms, organic <!ontents and their 

 changes, and such pro])erties as predicate the fuel value of woods, its ni.iiiiil'.ietiire into charcoal, its food 

 value, pulping (|ualities, etc. 



(c) Extractire mnleriah. 



A knowledge of these underlies the appli<'atiou of wnod in Ibc uianufactuie i>!' tan extracts, resin, and 

 turpentine, t.ar, gas, alcohol, acids, vanillin, <'tc. 



(d) Antiseptic materials. 



A knowledge of those chemical ])roperties which i)redicate durability and nridiTlie ]U'ocesses of increasing 

 the same. 



(e) Mineral constituents. 



A knowledge of these in ])articular will establish the relation of wood growth to ndneral constituents of 

 the soil and also serve as b.asis for certain technical uses (potash). 



