At the same time Prof. Andrews' experiments imply that,
supposing the temperature to be lowered to the point at which
liquefaction becomes possible, then liquefaction will take place where
there is first reached the required pressure. What are the corollaries
in relation to concentrating nebulous spheroids?

Assume a spheroid of such size as will form one of the inferior planets,
and consisting externally of a voluminous, cloudy atmosphere composed of
the less condensible elements, and internally of metallic gases: such
internal gases being kept by convection-currents at temperatures not
very widely differing. And assume that continuous radiation has brought
the internal mass of metallic gases down to the critical point of the
most condensible. May we not say that there is a size of the spheroid
such that the pressure will not be great enough to produce liquefaction
at any other place than the centre? or, in other words, that in the
process of decreasing temperature and increasing pressure, the centre
will be the place at which the combined conditions of pressure and
temperature will be first reached? If so, liquefaction, commencing at
the centre, will spread thence to the periphery; and, in virtue of the
law that solids have higher melting points under pressure than when
free, it may be that solidification will similarly, at a later stage,
begin at the centre and progress outwards: eventually producing, in that
case, a state such as Sir William Thomson alleges exists in the Earth.
But now suppose that instead of such a spheroid, we assume one of, say,
twenty or thirty times the mass; what will then happen? Notwithstanding
convection-currents, the temperature at the centre must always be
higher than elsewhere; and in the process of cooling the "critical
point" of temperature will sooner be reached in the outer parts. Though
the requisite pressure will not exist near the surface, there is
evidently, in a large spheroid, a depth below the surface at which the
pressure will be great enough, if the temperature is sufficiently low.
Hence it is inferable that somewhere between centre and surface in the
supposed larger spheroid, there will arise that state described by Prof.
Andrews, in which "flickering striae" of liquid float in gaseous matter
of equal density. And it may be inferred that gradually, as the process
goes on, these striae will become more abundant while the gaseous
interspaces diminish; until, eventually, the li