FREED FROM THE ACTION OF GRAVITY. 35 
the difference of the laws which govern the two sorts of attrac- 
tion appears not to influence the nature of the figure taken by 
the mass that turns upon itself. 
19. A liquid mass can only assume and preserve an annular 
form under the influence of a sufficient centrifugal force. Thus, 
as we have seen, when the resistance of the alcoholic liquid has 
diminished below a certain limit the velocity of rotation of the 
ring of oil, the latter, obeying the preponderating action of the 
molecular attraction, returns upon itself, loses its annular form, 
and re-constitutes itself into an entire mass, first ellipsoidal and 
then spherical. But if, by a method which I shall describe, we 
prevent the ring from agglomerating thus, and still leave the ac- 
tion of its centrifugal force to diminish, we then witness the ap- 
pearance of other phenomena well meriting interest. In order to 
produce them perfectly, in place of the disc of 35 millimetres, a 
dise of about 5 centimetres in diameter must be substituted*, 
which renders necessary, in order to form the ring well, a less 
velocity of rotation than with the preceding disc (the most suitable 
appears to me to bea little less than two turns ina second). Now, 
instead of stopping the movement of the disc at the instant when 
the ring has attained its greatest development, we must continue 
to move the handle. The film of oil will then break in a little 
time, as if the disc had been stopt; but the latter continuing to 
revolve in the alcoholic liquor, the portions of that liquor which 
are in contact with it will themselves assume a rotatory move- 
ment, and the centrifugal force which results from it will drive 
them continually towards the ring, so that the latter will not be 
able to return upon itself. Now, in these circumstances, we 
easily explained: the movement of rotation is communicated to the portions 
of the mixture which are nearest the axis above and below the mass of oil, 
before being able to communicate itself with the same intensity to the latter : 
hence, in the different points of this mass, there must result a less centrifugal 
force than in the points of the alcoholic mixture situated at the same distances 
from the axis of rotation. Thence a rush of the oil to the axis, and an elon- 
gation of the mass of the latter in the direction of this same axis. But, on 
continuing the rotation, the oil comes to receive the same movement as the 
surrounding liquid, and it also resumes gradually the spherical form. 
On stopping the flask, not suddenly, but in a rather rapid manner, I suc- 
ceeded once in obtaining a result sufficiently regular, and I observed, as I ex- 
pected, the sphere become flattened considerably in the direction of the axis of 
rotation. 
* This substitution is accomplished by detaching the upper end of the axis 
of the first disc from the large wire which passes through the metallic stopper 
(§ 8), and screwing in its place the end of the axis of the new disc. 
pg 
