On the Chemical Constituents of the Solar System. 379 



The results of ^ unitation ' may be conveniently applied to tho 

 verification of many numerical operations. The method of 

 unitation is practically equivalent to the theory of congruen- 

 cies; viz. the equation \]^x=^y would be written x^y (mod 6); 

 and many of the results are identical with those given by Gauss." 

 This statement is different from that contained in the paper (see 

 Phil. Mag. November 1876, p. 345 et seg.), and it has no 

 warranty from the author. The original title of the paper was 

 ^' On a new Mathematical Function ;" in compliance with a 

 simple request, and considering that the starting-point of the 

 paper was division-remainders, the author permitted the title 

 to be altered to " On Division-remainders in Arithmetic." 

 The statement in the ^ Report ' misinterprets the meaning of 

 the author — inasmuch as the paper w^as not intended to iden- 

 tify the function '\J^x=y with the statement ^' x divided by 3 

 leaves remainder y," but to point out the great distinction be- 

 tween the remainders in arithmetic and the periodic and dis- 

 continuous function JJsX. The symbol xiEE^y (mod S) does 

 not presuppose any function, but simply expresses a statement 

 which has for its basis the division-ren'iainders as obtained by 

 actual division, and therefore has no part with unitation. 

 OctoLer 8, 1877. 



LI. On some Points connected ivith the Chemical Constituents 

 of the Solar System. By J. H. Gladstone^ Ph.D., F.R.S., 

 Pres. C.S.* 



IN a recent course of lectures on the Chemistry of the 

 Heavenly Bodies, various considerations occurred to me, 

 which are not to be found in the ordinary treatises on the sub- 

 ject. I have since found that Mr. Norman Lockyer's recent 

 lecture at Manchester deals wdth some of these ; but the fol- 

 lowing are, as far as I am aware, novel, and may be worthy 

 of record as a contribution to a line of thought w^hich is being 

 at present considerably developed. 



I. The discoveries by means of the spectroscope, and the 

 general advance of knowledge of the heavenly bodies, have 

 tended greatly to confirm the nebular theory of the creation 

 of w^orlds. Assuming a hot nebulous mass made up of many 

 different chemical elements gradually condensing towards a 

 centre, the question arises. How Avill these elements be distri- 

 buted ? This would depend upon two different circumstances 



* Oommunicated by the Author, having been read at the British Asso- 

 ciation, August 1877. 



