T. S. Hunit—Celestial Chemistry. 127 
what analogous to that of clouds and rain to the aqueous vapor 
around us.’’* 
These views were reiterated in the preface to a second edition 
of my Chemical and Geological Essays, in 1878, and again before 
the British Association for the Advancement of Science at 
ublin,t and before the French Academy of Sciences in the 
same year.{ They were still further developed in an essay on 
the Chemical and Geological Relations of the Atmosphere, 
published in this Journal for May, 1880, in which attention was 
called to the important contribution to the subject by Mr. 
Lockyer in his ingenious and beautiful spectroscopic studies, 
the results of which are embodied in his “Discussion of the 
Working Hypothesis that the so-called Elements are Compound 
Bodies,” communicated to the Royal Society, December 12, 
1878. It was then remarked that the already noticed “ specu- 
lation of Lavoisier is really an anticipation of that view to 
which spectroscopic study has led the chemists of to-day ;” while 
it was said that the hypothesis put forth by the writer in 1874, 
“which seeks for a source of the nebulous matter itself, is per- 
of Newton that “the heavens are void of all sensible matter.” 
This statement is, however, qualified elsewhere by his assertion, 
that “to make way for the regular and lasting movements o 
the planets and comets, it is necessary to empty the heavens of 
all matter, except perhaps some very thin vapors, steams and 
effluvia arising from the atmospheres of the earth, planets and 
comets, and from such an exceedingly rare etherial medium as 
we have elsewhere described,” etc. (Optics, Book 111, Query 28). 
In order to understand fully the views of Newton on this 
subject, it is necessary to compare carefully his various utter- 
ances, including the Hypothesis, in 1675, the first edition of 
the Principia, in 1687, the second edition, in 1713, and the va- 
nlous editions of the Optics. This work appeared in 1704, the 
third book, with its appended queries, having, according to its 
author’s preface, been “ put together out of scattered papers” 
* A Century’s i i i i at Northum- 
berland, Pens, July's1, 1614; Amer, Chemist vol ¥, Po. 46-81, and Pop. Sci 
aye Monthly. ’ vi, p. . 
t Nature, Aug. 29, 1878, vol. xviii, p. 475. 
+ Comptes Rendus, Sept. 23, 1878, vol. xxxviii, p. 452. 
