of Liquids to each other. 313 



phon, with one of its capillary arms provided with a 

 scale for measuring the height of the liquid in this arm 

 above the level of the top of the column in the large 

 arm ; for it is now well established, by the results of 

 conclusive experiments, that the heights to which vari- 

 ous liquids rise in the same capillary tube are in pro- 

 portion to the degrees of force with which the particles 

 of the several liquids adhere to each other. 



The experiments for determining the diminution pro- 

 duced in this force by a given increase of temperature 

 demand more complicated apparatus and special care. 

 The apparatus which I have used in this research is 

 before the Class. Since, in the present state of the physi- 

 cal sciences, we can hardly flatter ourselves that we are able 

 to take a single step in advance, except with the aid of 

 instruments devised with care and executed with the 

 utmost precision, I always regard it as a duty to afford 

 the Class an opportunity of judging, by its own obser- 

 vation, of the excellence of those used by me in such 

 new experiments as I have the honour of describing to 

 the Class. 



I will show, presently, the way in which this appara- 

 tus is used, and I will give to the Class, at a subsequent 

 sitting, the account of the results of the experiments in 

 which it has been employed. 



I will conclude this memoir with some observations 

 on a very important point, which should, perhaps, be 

 still further elucidated. 



I have shown how I have proceeded in measuring 

 that sort of adhesion of the particles of water to each 

 other which produces the viscosity of this liquid, that 

 is, the force which must be exerted in order to cause 

 those particles to move on each other ; but we must 



