90 Prof. J. Le Conte on the Freezing of Vegetables. 
essential condition of success in the experiment, is, that it must 
be cooled without the siightest agitation, and no angular body 
be in contact with it; for the instant any solid body is dropped 
into water cooled below its freezing point, or a tremor is commt 
nicated to it, congelation commences and the temperature starts 
up to 32° Fahr.* It is very obvious, that this necessary conii 
tion is most effectually secured, by placing the water in capillar 
tubes ; for the adhesion of the fluid to the sides of the tubes, must 
tend to maintain it in that state of absolute repose upon which 
Dr. Thomas — 
of trees and shrubs, we have no means of ascertaining how fat 
the indispensable condition of absolute repose may be subverted 
by the perpetual agitation to which their branches and more flex- 
ible parts are subjected, through the action of winds. But it 
seems to me, that in the case of plants, the distribution of the 
—that the interior of the trunks of large trees possesses, during 
winter, a temperature considerably above that of the surrounding 
atmosphere. It has, likewise, been shown, that this heat is 
mm Summer, and imbibing moisture which must necessarily pal” 
take of this influence. 
ternal parts of large trees, retain a temperature which is about 
equal to that of the soil at the mean depth to which their roots 
penetrate.{' There can be no doubt that this is the chief cause 
of the uniformity of temperature of the interior of the trunks of 
* Graham's Elements of Chemistry. Am, ed. Philad., 1 et 51. 
t Vide Heat and Electricity. Deaeesinn p. 175." rim a an 
ale © Végétale. Tome ii, p. 879, et seq, Also, tome iii, pp. 1101, 110% 
