OtV8K 



FOREST! 



Of 

 UNIVCRSiTY OF CAUFOR 



THE SPECIFIC HEAT OF WOOD. 



IMPORTANCE OF DETERMINING THE SPECIFIC HEAT OF WOOD. 



The specific heat of wood that is, the heat capacity of a given 

 weight of wood compared with the heat capacity of the same weight 

 of water is one of the fundamental physical properties which indi- 

 cate its intrinsic nature and ultimate structure. The need for 

 reliable knowledge of this property was first revealed by a study of 

 dry-kiln operations. Different operators use different methods in 

 drying the same material for the same purpose; and, although their 

 methods differ only in detail, their conceptions of the manner in which 

 drying takes place differ enormously. In spite of the high grade of 

 intelligence and engineering skill devoted to the operation of the 

 larger kilns, the results are in no case entirely satisfactory. The 

 cause is the lack of familiarity with the minute structure and physical 

 properties of wood. In fact, there are no reliable values for those 

 physical properties which control the transfer of heat 1 or water 

 through wood. Knowledge of the specific heat of wood is necessary, 

 however, not only in dry-kiln operation, but also in solving certain 

 problems of the preservative impregnation of wood, the distillation 

 of wood, and of all processes in which wood is subjected to a change 

 of temperature. Though this study aimed solely to secure reliable 

 values for specific heat, 1 it is hoped that it may also direct attention 

 to the study of the other fundamental physical properties, so that 

 eventually a basis may be secured for the formulation of a rational 

 theory of the nature and ultimate structure of wood and of its action 

 under different treatments. While the results are of practical service 

 in commercial practice, they are even more useful in laboratory 

 experiments. 



APPARATUS AND METHODS. 



The specific heat was determined by measuring in a calorimeter 

 the quantity of heat given off by small cylinders of oven-dry wood 

 in falling from a temperature slightly above that of boiling water to 

 that of melting ice. The result in calories, divided by the difference 



i Prof. William Kent, in "The Mechanical Engineer's Pocketbook" (8th edition, 1910, p. 536), gives 

 the specific heats of four species of wood, the values ranging from 0.467 to 0.650. Prof. Kent does not cite 

 the source of these figures, but they appear to rest on determinations made by J. R. Mayer, of Heilbronn, 

 a contemporary of Joule. Cf. P6clet, E. Traite de la Chaleur, 4th edition, 1878, Vol. I, p. 606. 



7 

 38170 Bull. 11012 2 



