the true Sap of Trees is deposited during Winter. 93 
I had anticipated, and it was not till I had suspended and taken 
off from the balance each portion, at least ten times, that I 
ceased to believe that some error had occurred in the experi- 
ment : and indeed I was not at last satisfied till I had ascertained 
by means of compasses adapted to the measurement of solids, 
that the winter-felled pieces of wood were much less than the 
others which they equalled in weight. 
The pieces of wood, which had been the subjects of these 
experiments, were again put to dry, with other pieces of the 
same poles, and I yesterday ascertained the specific gravity of 
both with scarcely any variation in the result. But when I 
omitted the medulla, and parts adjacent to it, and used the 
layers of wood which had been more recently formed, I found 
the specific gravity of the winter-felled wood to be only 0.583, 
and that of the summer-felled to be 0.533 '■> an d trying the 
same experiment with similar pieces of wood, but taken from 
poles which had grown on a different stool, the specific gravity 
of the winter-felled wood was 0.588, and that of the summer- 
felled 0.534. 
It is evident that the whole of the preceding difference in 
the specific gravity of the winter and summer-felled wood 
might have arisen from a greater degree of contraction in the 
former kind, whilst drying ; I therefore proceeded to ascertain 
whether any given portion of it, by weight, would afford a 
greater quantity of extractive matter, when steeped in water. 
Having therefore reduced to small fragments 1 000 grains of 
each kind, I poured on each portion six ounces of boiling 
water ; and at the end of twenty-four hours, when the tem- 
perature of the water had sunk to 6o°, I found that the winter- 
felled wood had communicated a much deeper colour to the 
