NOTES ON THE PROPERTIES OP WOOD. 5 



carbon, forms carbonic acid gas, and the fibre, under the influence of the 

 latter, is changed into white dust. 



As an example of this, I may instance the wooden ceilings of houses 

 which after some time go into that state. The chief cause is, that the 

 free access of the air to the wood is prevented, and the little dampness 

 occasioned by washing is sufficient to promote the dry rot. 



The sap of wood contains some saccharine matter, which will 

 naturally decompose in itself, and this is noticed in timber stores from 

 the sour taste and smell of such woods. 



The actual time which wood; lasts depends in a great measure on 

 the'time when it was felled, and in how far the soil in which it grew 

 was suitable for its development. As a rule, wood cut in summer 

 is less durable than that felled during the winter months. 



It will also be the case with trees which remain a longer period 

 before their removal in the forest after being cut ; however, a great 

 difference does not exist between ripe woods, whether they are felled in 

 the summer or winter time, because the formation of the leaves and the 

 blossoms affects only the sap-wood and the bark of the tree ; therefore, 

 if the sap-wood is cut off, and the heart-wood is properly treated and 

 seasoned, the quality of the summer wood would be eqtial to that cut in 

 winter time. In support of this, I may mention that most of the trees 

 in Southern Italy are felled in July and August. 



The pines in the German forests are cut down mostly in summer, 

 and their wood is generally very sound. The opinion that this causes 

 dry-rot is, I think, unfounded, for I believe whenever this takes 

 place, it is in consequence of unseasoned timber being used. Con- 

 sidering the large quantity of timber imported into this country, I must 

 mention that my experience tends to show that the North American 

 woods, with the exception of red pine, are less durable than those from 

 the north of Europe. The latter are stronger, superior, and not so much 

 subject to dry-rot as the former. 



In the earlier portion of this paper, I had occasion to mention some 

 enemies of the wood which attack it while growing ; it is lucky that 

 they are neutralized and destroyed to a great extent by other animals in 

 the forest; and among those doing great service in this respect let us 

 remember the woodpeckers, finches, swine, hedgehogs, badgers, frogs, 

 and many others. 



Dry or dead wood has also some terrible foes, which at times cause 

 alarming ravages ; and unfortunately no effectual means have as yet 

 been found to check them : the most dangerous of these are the Termites, 

 the Lymexylon, the Sirex gigcts, the Teredo, and the Lymnuria terebrans. 



It is sometimes difficult to distinguish good from bad timber, and I 

 would therefore draw notice to some illustrations from a work published 

 by the French Government, — " Instructions sur le Bois de Marine," with 

 special reference to the oaks, and to which the following explanation 

 may serve. 



