Such figures have been
termed submergence cohesion figures; they are vortex rings. I have
solidified such vortex rings in their first stage of formation. If
drops of melted sulphur, at a temperature above that of the viscous
state, be let fall into water, the drops will be solidified in the
effort to form the ring, and the circular button, thick in the rim and
thin in the center, may be regarded as a solidified vortex ring of
plastic sulphur.
_4. That a Submergence Cohesion Figure is a Vortex Ring._
It may be shown that the conditions of the formation of a submergence
cohesion figure are those which exist in the formation of an aerial
vortex. Those conditions in their greatest perfection are (1) a
spherical envelope of a different nature from the medium in which the
rings are produced; (2) a circular orifice opening into the medium;
and (3) a percussive impact on the part of the sphere opposite the
orifice. In the production of vortex rings of phosphorus pentoxide in
the making of phosphoreted hydrogen, the spherical envelope is water,
the orifice the portion of the bubble which opens into the air
immediately it rises to the surface, and the impact is furnished by
gravity. So, also, in the case of a submergence cohesion figure, the
spherical envelope is the air surrounding the drop, the orifice the
portion of it which first comes in contact with the liquid at rest;
and here again the impact is due to gravity more directly than in the
former case.
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