let ween some Kinds of Flu'ids. j 55 



ferent journals*, and particularly in my answers to Pre- 

 vostt, and in some letters written to professor Bragnatelli, 

 insisted on the real explanation of the phcenomcna of this 

 kind ; proving, hy decisive experiments, tliat these move- 

 ments, thoiiirht to be the efiect of a repulsive power, arise 

 jtll from the same principle, that is to say, the atlrcKtion of 

 surface', whence it results, that one fluid being attracted 

 more than another, retires from the surface on which it 

 had extended itself, and obeys its own cohesion or force of 

 aggregation, and concentrates itself. 



I have lately resumed this subject, and have exiiibited it 

 in a clearer point of view, in the Transactions of the Italian 

 Society ofthe Sciences, proving, with the greatest vigour, that 

 it is the attraction of the surface which gives rise to the pre- 

 tended repulsions of some fluids on the surface of fluids, 

 and of some fluids on the surface of solids. 



Professor Brugnatelli, extending my experiments on the 

 attraction of surface, spoke of the repulsions reccntlv ob- 

 served by M. Drapainaud ; for he remarked, that several 

 fluids thrown in drops on the smooth surface of solids repel 

 oil, spirit of wine, oil of turpentine, and ether %• 



M. Draparnaud says that aicohol or spirit of wine expels 

 water and other liquids from the bottom of vessels, because 

 there is a continual emission of subtle parlicles. which, 

 forming an atmosphere, produce the removal of lliC water, 

 as Prevost said of odoriferous atmospheres : and, according 

 to him, all volatile bodies arc capable of doing the same at 

 the common temperature of the atmosphere, since he is of 

 opinion that they act mechanically, that is to say, by means 

 of the impulsion of their emanations. 



But I shall beg leave to oppose to him some facts, and 

 some reasoning U) throw light on this truth. Water, iu- 

 (Jeed, retires from the surface of the vessel to which spirit 

 of wine is applied ; but it is not true that it is expelled bv a 

 repulsive. foice. It is equally false, that the space abandoind 

 ijy the water, when the experiment is made, is perfectly dsv, 

 as M, Draparnaud says; but the water is succeeded bv a 

 light strjitum of spirit of wine, which feoon evaporates. 

 Water, as well as the other fluids, adduced by DraiKiruaud, 

 retire, because they arc obliged to give up the surface to the 

 spirit <jf wine, winch has a greater attraction for it t'lau 

 ihev, and seizes on it with moie energy : being thus aban- 



* Giorn. Itulinni cr Jrurnal de Physiouc ; Anmlcs ilc Cliimic. 

 t Aim. Chim. ili PH»ia. torn, xix; AniKiles dt Ciiimi'.', no. (43. 

 \ Aj!.".. di Child, di Tavia, ton;, xviii. 



duned 



