596 PLATEAU ON' THE PHENOMENA OF A FREE LIQUID MASS 



pump, to remove, for instance, a portion of the oil composing 

 the liquid mass, when it is required to diminish the volume of 

 the latter, or to withdraw the enth'e 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 with 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 with- 

 out any of it remaining upon the spatula. This is the purpose 

 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 evapo- 

 rating, would leave the small quantity of oil which it held in 

 solution upon their surface ; and Mhen the same 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 experi- 

 ments 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 covering the bottom with a square piece of 

 linen. 



New experiments in support of the theoretical principles brought 

 forward in the preceding observations. Figures of equilibrium 

 terminated by surfaces of spherical curvature. New principle 

 relating to layers of liquids. 



10. The facts which we shall first describe may be considered 

 as constituting the experimental demonstration of the principle 

 of the superficial layer (§6 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 envelopes 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 



