110 Notes on the Properties of Wood. 
When trees arrive at a certain age, they should be cut 
down, that is, if itis intended their wood should be of a 
good and durable quality. If left growing, the quantity 
will certainly increase, but the quality will suffer in an 
inverse ratio. 
The colonr of wood is a prominent feature, with the 
various species, as also of the quality of the wood. If a 
tree is felled in a rainy or damp atmosphere, say during a 
mild winter season, the heart of the wood will then retain 
its natural wet colour for a longer period. Ina dry spring 
atmosphere the heartwood dries sooner, although the sap- 
wood retains its moisture longer than the ripewood of the 
stem. By this latter process the moisture evaporates and 
draws towards the bark, by which the sapwood sometimes 
takes the darker colour ‘of the ripewood. ‘The atmosphere 
fully develops the proper colours of the various woods after 
they have been exposed to its influence for some time. 
The period when timber may be said to be highest in 
colour, is during the time when the tree is in full bloom. 
If the colour of an oak is of one cast, it is the sign of its 
good condition, but it must be of the same shade in tke 
ripewood as well as inthe yearly rings. A proper judg- 
ment upon the condition of the wood can only be given 
when the tree is forested. 
The scent of some woods enable us to pass a judgment 
upon their condition. In the early Spring, old white. 
Poplar trees (Populus alba), give forth an obnoxious smell, 
which proceeds from the sap flowing from the decayed 
interior to the outside. Pinewood retains its natural smell 
for years. Leafwood trees have a sour smell, and the 
stronger it is the healthier the wood. Should the smell be 
faint the tree is dying off. 
We now come tothe sap or blood of the tree, which 
circulates in it, promotes its life, and is composed mainly 
of oxygen, hydrogen, carbon, nitrogen, and sulphur. The 
sap forms a considerable body in the green or fresh wood, 
changing, more or less, the quality of the wood, the inti- — 
mate study of its influences being of great technical impor- 
tance. It has been said that the sap flows out of a tree 
after it is cut down. Tffis is only the case with very few 
woods, as, with most of them, the moisture evaporates. 
The amount of sap considerably changes during the > 
seasons of the year. A fine example of this is furnished 
usin awork called “ Exploitation des Bois,” by M. Duhamel _ 
de Monceau, and which we extract from a pamphlet by M. 
Ie 
