WITHDRAWN PROM THE ACTION OP GRAVITY. 233 



stance, a portion of the oil composing tlie liquid massi, when it is required to 

 diminish the volume of the latter, or to withdraw the entire mass of oil from the 

 vessel, an operation which is sometimes required, &c. In the second place, two 

 wooden spatulas, one being slightly bent, the other straight, covered with fine 

 linen or cotton stuff. When these spatulas are introduced into the vessel, and 

 the cloth Avith which they are furnished is thoroughly impregnated with the 

 alcoholic liquid, the mass of oil does not adhere to them. Hence, by means of 

 one or the other of these spatulas, the mass can be moved in the surrounding 

 liquid, and conducted to the place which it is required to occupy in the interior 

 of the vessel without any of it remaining upon the spatula. This is the pur- 

 pose for which these instruments are intended. After they have been used, 

 care must always be taken to agitate them in pure alcohol before allowing 

 them to dry. If this precaution be omitted, the alcoholic mixture with which 

 they are impregnated, on evaporating, would leave the small quantity of oil 

 which it held in solution upon their surface; and when the ^ame instruments 

 are used again, the mass of oil would adhere to it. In the third place, an iron 

 spatula, the uses of which we shall point out in the proper place. Lastly, as it 

 is necessary, in all the experiments which we shall relate, that the alcoholic 

 liquid should be homogeneous, the process indicated in the preceding memoir 

 (§ 25) cannot be used to prevent the mass of oil from becoming occasionally 

 adherent to the bottom of the vessel ; but the same result is obtained by cover- 

 ing the bottom with a square piece of linen. 



New experiments in support of the theoretical 2>rinciples hrought forward in the 

 preceding obscrrations. Figures of equilibrium terminated by surfaces of 

 spherical curvature. New j^ri'icijile relating to layers of liquids. 



10. The facts which Vi^e shall first describe may be cousidered as constituting 

 the experimental demonstration of the principle of the superficial layer, (§ G, bis.) 

 Let us imagine any solid system to be immersed in the liquid mass, and let us 

 give to this mass such a volume that it may constitute a sphere which com- 

 pletely envelops the solid system without the latter reaching the surface at any 

 point. Then, if the above principle be true, the presence of the solid system 

 will exert no influence upon the figure of equilibrium, because, under these 

 circumstances, the superficial layer, from Avhich the configuring actions emanate, 

 remains perfectly free ; whilst if these actions emanated from all points of the 

 mass, any unsymmetrical modification occurring in the internal parts of the 

 latter would necessarily produce one in the external form. This is confirmed 

 by experiment. The condition of a solid system completely enveloped by the 

 mass of oil would be somewhat difficult to realize ; but it must be remembered 

 that, in the experiments relating to the preceding memoir, the system of the disk, 

 by means of which the mass was made to revolve, was very nearly in this con- 

 dition, because it did not reach the external surface of the mass excepting at 

 the two very small spaces which gave passage to its axis. But we then saAv 

 (§ 9 of the preceding memoir) that when the mass was at rest, its sphericity 

 was only very slightly altered by the presence of this system. The theoretical 

 condition may be more nearly approached by taking a very fine metallic Avire 

 for the axis of this same system ; in this case the alteration in form is quite 

 imperceptible. The axis being supposed to be vertical, the disk may, moreover, 

 be placed so that its centre coincides Avith that of the mass of oil, or is situated 

 above or below the latter Avithout producing any difference. I shall relate 

 another fact of an analogous nature. In the course of the experiments, it some- 

 times happens that portions of the alcoholic liqvxid become imprisoned in the 

 interior of the mass of oil, forming so many isolated spheres. Now, hoAvever 

 these spheres may be situated in the interior of the mass, not the least alteration 

 is produced in the figure of the latter. 



