1881.] from, the time of Newton. 131 



coveries in spectroscopy and in stellar chemistry, has been well 

 set forth by Lockyer in his late lectures on Solar Physics 1 , where 

 however the generalization is described as having been first made 

 by Brodie in 18G7. A similar but later enunciation of the same 

 idea by Clerk-Maxwell is also cited by Lockyer. Brodie, in fact, 

 on the 6th of June, one week after my own lecture, gave a lecture 

 on Ideal Chemistry before the Chemical Society of London, pub- 

 lished in the Chemical News of June 14th, in which, with regard 

 to his ideal elements, in farther extension of the suggestion already 

 put forth by him in the extract above given from his paper of 

 May 6, I860, he says "we may conceive that in remote ages the 

 temperature of matter was much higher than it is now, and that 

 these other things [the ideal elements] existed in the state of 

 perfect gases — separate existences — uncombined." He farther 

 suggested, from spectroscopic evidence, that it is probable that 

 "we may one day, from this source have revealed to us inde- 

 pendent evidence of the existence of these ideal elements in the 

 sun and stars." 



During the months of June and July, 1867, I was absent on 

 the continent, and this lecture of Brodie's remained wholly un- 

 known to me until its republication in 1880, in a separate form by 

 its author 2 , with a preface, in which he pointed out that he had 

 therein suggested the probable liberation of his ideal elements 

 in the sun, referring at the same time to his paper of 1866, from 

 which we have already quoted the only expression bearing on the 

 possible independence of these ideal elements somewhere in time 

 or in space. 



The above statements are necessary in order to explain why 

 it is that I have made no reference to Sir Benjamin Brodie on the 

 several occasions on which, in the interval between 1867 and the 

 present time, I have reiterated and enforced my views on the great 

 significance of the hypothesis of celestial dissociation as giving rise 

 to forms of matter more elemental than any known to us in ter- 

 restrial chemistry. The conception, as at first enunciated in some- 

 what different forms alike by Brodie and myself, was one to which 

 we were both naturally, one might say, inevitably led by different 

 paths from our respective fields of speculation, and which each 

 might accept as in the highest degree probable, and make, as it 

 were, his own. I write therefore in no spirit of invidious rival ry 

 with my honoured and lamented friend, but simply to clear myself 

 from the charge, which might otherwise be brought against me, of 

 having on various occasions within the past fourteen years, put 

 forth and enlarged upon this conception without mentioning Sir 



1 Nature, Aug. 25, 1881, Vol. xxiv. p. 396. 



2 Ideal Chemistry, a Lecture. Macmillan, 1880. 



