Notes on the Properties of Wood. Itt 
Justen, recently published. M. D. de Monceau, had felled 
during the year 1732-33 eight oaks each month, of equal 
age, from which he obtained the following results :— 
Pounds Month. 
340°718 aa oe wes December. 
340°906 ne ae ie January. 
328031 eh We bey February. 
331°087 ne sas safe March. 
NebLS75 we a ae April. 
319°500 ee ahs re May. 
297°312 Ae bg? Pe June. 
297.250 “at oF set July. 
314'469 a * my August. 
306°875 se ga we September. 
328°906 7 - awe October. 
331000 a se ae November. 
From these figures, which are Parisian weight, we find 
that during December and January the trees had more sap 
than during the other months. The sap diminishes in 
October, November, February, and March, in April it is 
less than the four months above enumerated, and is least 
in the months of June and July. Another experiment was 
made with six young oaks, in which the December wood 
again had most sap, thus proving that there is more sap 
in the December wood. The least amount of sap being 
contained in the July and August wood. 
Heavy hardwoods lose, by drying, about one-third of 
their original weight; lighter woods lose from about one- 
third to one-half, being to, in some degree, dependent on 
the soil where they grow. The bark prevents the sap from 
running out of the stem. Experiments have proved that the 
weight of wood with its bark on, greatly fluctuate, where- 
as, the weight of wood without its bark, steadily diminishes. 
Wood never loses all its sap. When air-dry it generally 
has 20 per cent. of its weight, 
The preceding portion of the article has been culled 
from a work by M. Joseph Justen, of Liverpool, the follow- 
ing we extract 72 ertenso :— : 
It is of importance to know how long various timbers of 
different dimensions and strength will take to become air- 
dry, that is to say, how soon will they arrive at the medium 
weight which they maintain for always, and to which they 
return whenever the influence of the atmosphere alters it. 
