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DR GEORGE WILSON ON THE FINITE DIVISIBILITY OF MATTER. 81 



appear that it had not extended to any one, still more, if not to several, it would 

 suffice to prove that it was not infinitely divisible. In short, our atmosphere 

 being the self-dividing mass, and all the stars standing between it and infinity, 

 the absence of an atmosphere like the earth's, from any one of them, shews that 

 that it can only be finitely divided ; and the decision in the negative of the ques- 

 tion of infinite divisibility should have dated from the discovery of the telescope, 

 and Galileo's earliest observation of the eclipses of Jupiter's moons. 



My object in the following remarks, is to shew that Wollastons identification 

 of the divisibility of the molecule, with the observed division of the mass of which 

 it is a part, is altogether unwarrantable ; that he takes for granted the very thing 

 to be proved ; and that his whole discussion leaves the question of the finite or 

 infinite divisibility of matter exactly where it found it. Before doing so, however, 

 I am anxious to refer very briefly to the criticisms already offered on this part of 

 the paper under discussion. 



The opinions hitherto expressed as to Wollaston's argument may be arranged, 

 I believe, under four heads. 1st, A few natural philosophers have entirely assented 

 to the truth of the conclusion contained in it. Among these was Daubeny,* who 

 has lately, however, withdrawn his assent ;f and it is still advocated by Dumas, 

 who, whilst he objects to Wollaston's arguments, on other grounds which will be 

 referred to immediately, appears to consider the conclusion of the latter unavoid- 

 able, if his premises are granted him.| 



2d, A greater number, including Faraday,^ Graham, || and Turner,^ have 

 implied, by the terms of commendation in which they have referred to it, that at 

 least they detected no fallacy in the argument. 



3c/, It has been objected to by Dumas (following out the views of Poisson), 

 on the ground that the low temperature which is known to prevail in the upper 



* Introduction to the Atomic Theory, 1831, pp. 103-5. 



t Supplement to Introduction, &c., 1840, p. II. 



J Dumas' assent was entirely negative, but was strongly manifested, and is the more remarkable, 

 that he has directed special attention to the phenomena presented by those gases which combine without 

 undergoing diminution of their volume, as irreconcilable with the idea of the chemical equivalents of 

 tliese bodies being represented by single atoms, siich as Dalton assumed, (Lefons sur la Philosophie 

 Chimique, p. 263). Had this view been carried out and applied to the atmosphere, it would have 

 struck at the root of Wollaston's whole train of reasoning, and would have obviated the necessity of 

 appeal to the questionable views of Poisson, as to the cause of the limitation of the atmosphere. As 

 Whewell's discussion of Wollaston's speculations, which was specially intended to meet the argument 

 of Dumas, has appeared since the latter published his views, it may have led to some modification of 

 his opinion. But that distinguished chemist has not had occasion, so far as I am aware, to refer again 

 to the subject in public ; so that, in the meanwhile, I include him among the acknowledged supporters 

 of the intrinsic validity of Wollaston's views. 



§ On the existence of a limit to vaporisation, Phil. Trans., 1826, p. 492, 



II Elements of Chemistry, pp. 68 and 273. 



f Elements of Chemistry, 7th edition, p. 207. 



VOL. XVI. PART 1. X 



