Electric Light in Medicine. 419 
A tube 1:20 metres long filled with plaster and terminated at the summit 
by an evaporating surface is inserted by its base into a reservoir closed 
tres of mercury or by 200 or 270 millimetres of water ; and the water 
appears even at the upper extremity of the tube, which proves that por- 
ous bodies are able to raise water higher than can be done by atmospheric 
re, ‘These facts cannot be explained by the ordinary laws of capil- 
lary attraction, since these bodies are not formed of impermeable tubes, 
t of corpuscles in juxtaposition, separated by ‘small empty spaces. 
Jamin has therefore submitted the problem to the calculus and has come 
to results, of which we mention the following: 
If in a damp porous. body, the water is compressed by a power of seve- 
tal atmospheres, it can congeal only at a temperature below 0° C.* 
ae the old wood is able to resist frost, while the young shoots 
being less dense are unable to j ; 
Since water in filtering through a porous body is compressed as it 
enters and dilates again as it runs out, it should exhibit electric currents 
and many other phenomena. 
@ theory can not be applied to non-homogeneous porous bodies. In 
the extended memoir which he has prepared, Jamin discusses the compli- 
cated results which may be occasioned by. irregularity of structure; he 
makes an application of it to wood, and shows that the interior pressure 
must be augmented in the denser tissues ; that the air must come from 
the larger tubes, which cannot serve for the ascent of the sap. 
It is plain that the evident tendency of all these experiments is to ex- 
plain the ascent of the sap in vegetables by capillarity. The idea is not 
new, but it has not been hitherto fully admitted, notwithstanding the 
experiments which have been heretofore made. : 
Jamin gives it probability in showing by decisive experiments, that 
porous bodies exercise a eapilla action superior to the pressure of t 
1 in diagn t 
iasmuch as the illumination is insufficient, or the light is more or les 
i ied wi t. It isnot the ordinary electric light 
tol spoken of, but that produced by induced currents. The problem to be 
whick consists in finding a source of light with little or no heating effect, 
can be I J into tubes of small capacity and of forms adapted 
an fact j fr ter contained in 
pillary has just been demonstrated by Mr. Sorby for wa 
‘pilary tubes of ‘a small diameter.—s. ¥. 
