32 MOLECULAR ATTRACTION. L.ECT. II. 



ratio than that of the diminished density produced by the 

 heat. 



lOthly. The elevations and depressions of which we have 

 just now spoken, are independent of the density of the 

 liquids. Thus, if we represent by 100 the elevation of 

 water in a tube, that of alcohol will be 40, that of the vola- 

 tile oil of lavender 37, and that of a saturated solution of 

 common salt 88. 



llthly. Two bodies within a certain distance of each 

 other, and floating upon a liquid, mutually attract each 

 other and adhere, provided that both or neither of them be 

 susceptible of being moistened. If one only be susceptible 

 of being moistened, they repel each other. On this prin- 

 ciple we explain the tendency possessed by small light 

 bodies floating on water, to approach the sides of the vessels 

 containing them. 



12thly. Whatever be the height to which a liquid rises 

 it never flows over the upper opening of the capillary tube. 

 This indeed is a necessary consequence of the facts already 

 stated. For it must be remembered that the surface of the 

 column of liquid elevated in the tube is always concave 

 outwardly. Hence if we pour water into one leg of a bent 

 capillary tube until the column terminates by a surface at 

 first horizontal, then convex outwardly, it will be found 

 that the other column of liquid remained concave, and is 

 constantly more elevated than the other. Thus then, in the 

 phenomena of capillarity, a force of depression is developed 

 when the surface becomes convex. Do not suppose that 

 the water which drips from a wick of cotton moistened 

 with this liquid, and of which one end is bent downwards, 

 does so by reason of capillarity ; for we have only to hold 

 the wick horizontally, and the discharge immediately 

 ceases. 



Theory. I cannot dwell on these phenomena so far as to 



