436 Molecular Physics in High Vacua. [June, 
proposed ? We find in these phenomena confirmation of 
the modern views of matter and energy. The fa< 5 ts elicited 
are in harmony with the theory that matter is not continuous 
hut composed of a prodigious number of minute particles, 
not in mutual contact. The faCts also are in full accordance 
with the kinetic theory of gases — to which I have already 
referred — and with the conception of heat as a particular 
kind of energy, expressing itself as a rapid vibratory motion 
of the particles of matter. This alone would be a lesson 
of no small value. In Science, every law, every generalisa- 
tion, however well established, must constantly be submitted 
to the ordeal of a comparison with newly-discovered pheno- 
mena; and a theory may be pronounced triumphant when 
it is found to harmonise with and to account for faCts which 
when it was propounded were still unrecognised or un- 
explained. 
But the experiments have shown us more than this : we 
have been enabled to contemplate matter in a condition 
hitherto unknown, — in a fourth state, — as far removed from 
that of gas as gas is from liquid, where the well-known 
properties of gases and elastic fluids almost disappear, whilst 
in their stead are revealed attributes previously masked and 
unsuspected. In this ultra-gaseous state of matter pheno- 
mena are perceived which in the mere gaseous condition are 
as impossible as in liquids or solids. 
I admit that between the gaseous and the ultra-gaseous 
state there can be traced no sharp boundary; the one 
merges imperceptibly into the other. It is true also that 
we cannot see or handle matter in this novel phase. Nor 
can human or any other kind of organic life conceivable 
to us penetrate into regions where such ultra-gaseous 
matter may be supposed to exist. Nevertheless, we are able 
to observe it and experiment on it, legitimately arguing 
from the seen to the unseen. 
Of the practical applications that may arise out of these 
researches, it would be now premature to speak. It is rarely 
given to the discoverer of new faCts and new laws to wit- 
ness their immediate utilisation. The ancients showed a 
perhaps unconscious sagacity when they selected the olive, 
one of the slowest growing trees, as the symbol of Minerva, 
the goddess of Arts and Industry. Nevertheless, I hold 
that all careful honest research will ultimately even though 
in an indirect manner draw after it, as Bacon said, “ whole 
troops of practical applications.” 
