" Spheroidal Theory'' of the Interior of the Earth. 141 
fluid mass was, Dr Wright considered, fatal to Dr Macadam's 
ingenious and beautiful theory. 
A discussion followed on the subject of this paper, in which 
Dr Macadam, Dr M'Bain, Mr Khind, Dr Ferguson, and the 
Kev. Walter Wood, Elie, took part. 
Dr Macadam stated that, having been specially alluded 
to in connection with this paper, he w^as desirous of making 
a few remarks. He felt more and more convinced of the 
probable truth of the spheroidal theory of the central theory, 
and nothing which Dr Wright had advanced had shaken, in 
the slightest degree, his confidence in the theory as being 
able to explain satisfactorily the existence of a cold crust of 
solid matter surrounding a central nucleus in an intensely 
ignited state. The conclusions which Dr Wright had arrived 
at were not tenable, as the heated vessel on which the sphe- 
roid of water moved about was comparatively at a needlessly 
high temperature,* and experiments made by Boutigny upon 
ice had shown that, when thrown on a heated surface, a 
portion of the ice passed into the spheroidal state, and then 
continued to reflect heat, leaving the remaining part of the 
ice still frozen. t The arrangement of the crust and central 
* The temperature of the heated vessel in which water is thrown and passes 
into the spheroidal state, does not require to be above 339°-8 F. (340° F.) ; 
and it is manifest that a thin metallic capsule, with a Bunsen gas-lamp burn- 
ing immediately underneath, will be at a much higher temperature than 
340° F. The best mode of applying the heat to a vessel is to surround it by 
a bath of oil, the temperature of which can be easily regulated ; or place the 
vessel in a basin-shaped depression in a mass of fire-clay which has been pre- 
viously heated, and the temperature of which can be ascertained by a ther- 
mometer. Another mode of making experiments on the spheroidal state of 
matter, is to heat a solid ball of platinum before the oxyhydrogen blowpipe 
and plunge it into water, v^hen the liquid will be observed to stand back from 
the heated ball, and gradually, as the metal cools down, the water approaches, 
and ultimately, when the ball is reduced to 340 F., the water for the first 
time touches the metal, and passes rapidly into steam. 
t Boutigny will be acknowledged to be the principal authority on all ex- 
perimental data connected with the spheroidal condition of matter ; and his 
elaborate series of experiments and observations are not only conclusive, but 
may also be regarded as exhaustive of the subject. On the passage of ice 
into the spheroidal state, he says [Annales de Chimie, troisieme serie, tome 
onzieme) : — 
" Quarante-neuvihne experience. — On fait rougir la capsule en fonte dont on 
