WITHDRAWN FROM THE ACTION OF GRAVITY. 617 



pressure belonging to them might be equal to that which corre- 

 sponds to these same concave surfaces (§ 25). 



On removing still further portions of the liquid, the layer will 

 continue to enlarge, whilst the full mass which occupies the 

 middle of the figure will diminish in volume, and this mass can 

 thus be reduced to very minute dimensions : fig. 12 represents 

 the entire system in this latter state. It is even possible to 

 make the little central mass disappear entirely, and thus to ob- 

 tain a complete laminar system; but for this purpose certain 

 precautions must be taken, which I shall now point out. When 

 the central mass has become sufficiently small, the point of the 

 syringe must first be thoroughly wiped ; otherwise the oil ad- 

 heres to its exterior to a certain height, and this attraction keeps 

 a certain quantity of oil around it, which the instrument cannot 

 absorb into its interior. In the second place, the point of the 

 syringe must be depressed to such an extent, that it nearly 

 touches the inferior surface of the little mass. During the suc- 

 tion, this surface is then seen to become raised, so as to touch 

 the orifice of the instrument, and the latter then absorbs as 

 much of the alcoholic mixture as of the oil ; but this is of no 

 consequence, and the minute mass is seen to diminish by de- 

 grees, so as at last completely to disappear. The system then 

 consists of twelve triangular layers, each of which commences at 

 one of the wires of the frame, and all the summits of which 

 unite at the centre of the figure ; it is represented in fig. 13. 

 But this system is only formed during the action of the sy- 

 ringe. If, when this is complete, the point of the instrument is 

 slowly withdrawn, an additional lamina of a square form is seen 

 to be developed in the centre of the figure (fig. 14). This then 

 is the definitive laminar system to which the liquid cube is re- 

 duced by the gradual diminution of its mass. 



32. In the preceding experiment, as in that of paragraph 23, 

 the thickness of the layers is at first greater than that which 

 would correspond to equilibrium. If then the system were left 

 to itself whilst it still contains a central mass, we should imagine 

 that one portion of the liquid of the layers would be slowly 

 driven towards this mass, and that the layers would gradually 

 become thinner. Moreover it always happens that one or the 

 other of the latter increases after some time, undoubtedly for 

 the reason which we have already pointed out (§26). Hence, 

 for the perfect success of the transformation of the cube into the 



VOL. v. PART XX. 2 T 



