Conductibility for Caloric of ' different Woods, S^c 131 



oldest strata of the secondary formation, while they uninterrupt- 

 edly increase in the successive formations.* 



On the relative Conductibility for Caloric of different WoodSy 

 in the direction of their fibres, and in the contrary directum. 

 By MM. Aug. de La Rive, and Alph. De Candolle. 



X HE conductibility of the metals and some other substances 

 has long been a subject of Inquiry, on account of the important 

 results which it has furnished with reference to the arts and 

 sciences. There are other substances not less useful to be known 

 in this respect, such as glass, porcelain, and other products of 

 art, as well as woods of various kinds. A memoir by M. Des- 

 prez, inserted in the Annales de Chimie, has made known the 

 relative conductibilities of some of these substances. We have 

 thought that it would not be without interest to complete the 

 knowledge which we possess on this subject, by comparing the 

 conducting powers of certain species of wood. This compa- 

 rison may, besides, lead to various considerations relative to ve- 

 getable physiology. 



With this object, we procured well dried pieces of wood, of a 

 square form, 4 inches 10 lines long, 18 lines broad, and 1 inch 

 thick. To know the differences that might result from the direc- 

 tion of the woody layers, we had pieces sawn in the contrary direc- 

 tion to that in which wood is commonly wrought, that is to say, 

 the fibres being transverse, in place of being in the direction 

 coriesponding to the length of the piece of wood. It is this di- 

 rection contrary to the woody fibres that caloric follows, when 

 it passes from the atmosphere into the interior of a tree, or 

 vice versa. On one of the broad surfaces of these pieces of wood, 

 beginning at the distance of three centimetres from one of the 

 extremities, were bored, at equal distances of 9 lines, five holes, 

 7 millimetres in breadth, which reached only the middle of the 

 thickness of the wood. Into each hole we poured a little mer- 



" The second part of this Memoir will apjiear in next number of the 

 Journal. 



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