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XXVII. On the Equilibrium and Motion of Liquids in Porous 
Bodies. By M. J. Jamin*. 
ee function performed by vegetables, which consists in the 
raising of water through their tissues to their leaves, has 
never yet been explained. This effect, however, must either be 
due to the play of special organs analogous to the human heart, 
or it must be determined by the exercise of molecular forces and 
gravity in the ligneous body. If the first hypothesis were true, 
physiology would, in all probability, have detected at least the 
existence of the supposed organs; from its silence, therefore, 
we are led to conclude their non-existence. On the other hand, 
if the second hypothesis holds good, the question enters the 
domain of general physics, and may with justice be studied ex- 
perimentally with a view of imitating artificially this function of 
vegetables. 
Regarding the problem from the latter point of view, M. 
Jamin announces having arrived at a plausible solution. In this, 
his first communication, however, the author occupies himself 
solely with certain preliminary phenomena of capillarity in tubes 
and porous bodies; he proposes subsequently to apply the 
principles he here establishes and to describe an apparatus, ex- 
clusively composed of inorganic substances, which in its struc- 
ture presents a striking analogy to that of vegetables, and which 
possesses the property of raising water, as trees do, to a_height 
greater than that of the atmosphere between a moist soil, from 
which this water is continually drawn, and the artificial leaves 
where the water is continually evaporated. The conclusion he 
announces is that capillary forces suffice to explain the motion 
of the sap in vegetables. 
A capillary tube being taken, one of its extremities is put 
in communication with a vacuum ; by so doing a current of air is 
established within the tube from the atmosphere to the vacuum. 
If then the finger, covered with wet linen, be alternately pressed 
against, and lifted from the free extremity of the tube, the opera- 
tion being frequently repeated at very short intervals, columns 
of liquid separated by bubbles of air will traverse the tube with 
a velocity which, from being very great at first, will diminish as 
the operation proceeds, and finally become zero. A chaplet whose 
beads are air and water is thus obtained, and the apparatus thus 
prepared is found to possess peculiar properties. 
When a pressure is exerted at one extremity the nearest beads 
recede quickly, the following ones are less displaced, and the 
more distant ones remain unmoved. By doubling the pressure 
twice as many beads are put in motion ; or, more generally, the 
* From the Comptes Rendus, January 23, 1860. 
