O.y RADIANT MATTER. 13 



most sensitive of animals. A slight or a disappointment mortifies him 

 deeply. The elephants of South Africa, which are rough animals when 

 compared with those raised in captivity, die from diarrhoea or constipa- 

 tion, as Le Vaillant has stated. Their tamer brethren are free from 

 disease ; and, if they die before their time, they generally do so from 

 the above-mentioned causes. Sultan, the pride of the Jardin, the most 

 amiable elephant I ever knew, was unable to survive the death of his 

 companion, the pet dog Jean. 



OX RADIANT MATTER.* 



By WILLIAM CROOKES, F. E. S. 

 I. 



TO throw light on the title of this lecture I must go back more than 

 sixty years — to 1816. Faraday, then a mere student and ardent 

 experimentalist, was twenty-four years old, and at this early period of 

 his career he delivered a series of lectures on the general properties of 

 matter, and one of them bore the remarkable title, " On Radiant Mat- 

 ter." The great philosopher's notes of this lecture are to be found in 

 Dr. Bence Jones's " Life and Letters of Faraday," and I will here 

 quote a passage in which he first employs the expression radiant 

 matter : 



If we conceive a change as far beyond vaporization as that is above fluidity, 

 and then take into account also the proportional increased extent of alteration 

 as the changes rise, we shall perhaps, if we can form any conception at all, not 

 fall far short of radiant matter; and as in the last conversion many qualities 

 were lost, so here also many more would disappear. 



Faraday was evidently engrossed with this far-reaching speculation, 

 for three years later — in 1819 — we find him bringing fresh evidence 

 and argument to strengthen his startling hypothesis. His notes are 

 now more extended, and they show that in the intervening thi-ee years 

 he had thought much and deeply on this higher form of matter. He 

 first points out that matter may be classed into four states — solid, 

 liquid, gaseous, and radiant — these modifications depending upon dif- 

 ferences in their several essential properties. He admits that the ex- 

 istence of radiant matter is as yet unproved, and then proceeds, in a 

 series of ingenious analogical arguments, to show the probability of its 

 existencc.f 



* A lecture delivered before the British Association for the Advancement of Science, 

 at Sheffield, Friday, August 22, 1879. 



f I may now notice a curious progression in physical properties accompanying changes 

 of form, and wliic-b is perhaps sufficient to induce, in the inventive and sanguine philoso- 



