232 On Prof. Young's " Demonstration " of Newton's Rule, 



benzole, or bisulphide of carbon when those liquids are agitated 

 with mixtures containing it, leaving them nearly colourless, whilst 

 those substances themselves acquire an intense blood-red colour, 

 which, however, soon again disappears, evolving globules of gas. 

 Solutions containing the sulphocyanide of iron, on the other hand, 

 when agitated with those liquids, do not impart to them any 

 colour (except in the case of ether, which acquires a very faint 

 pinkish tint), whilst the solutions themselves remain of the same 

 intensity of colour as they possessed before the agitation with 

 those substances. So that in these, and many other characters I 

 have observed, there exists a wide difference in the properties of 

 these two compounds, and a further study of them may lead to 

 some new and interesting results. 



XXIX. Note to the Editors of the Philosophical Magazine and 

 Journal. By Professor Sylvester, F.R.S., fyc. 



K, Woolwich Common, 

 Gentlemen, August 9, 1865. 



IN answer to Prof. Young's remarks contained in the last 

 Number of your valuable Journal, I have only to observe that 

 I abide by the statement therein recorded as put forth by me 

 when invited by Prof. Young to express an opinion on his supposed 

 demonstration of Newton's rule, viz. that, " like all which had 

 gone before, it was a failure, and no proof at all." This 

 opinion is in no degree shaken or modified by the ingenious 

 rhetoric of the additional "two notes enclosed within brackets" 

 of his recent article. 



It was " not hastily formed," for I was in possession of Prof. 

 Young's pamphlet on the subject, dated 1844, lent to me by 

 Professor De Morgan, at or about the time (now a year or two 

 ago) when he suggested to me to seek for a proof of Newton's 

 rule, and have consequently reason to presume that that eminent 

 mathematician's opinion of the soundness of Prof. Young's logic 

 coincides with my own. I caused to be forwarded to Prof. Young 

 an invitation to attend my lecture, under the impression that, 

 after an interval of twenty years, his mind would have awakened 

 to a sense of the unsubstantial nature of his fancied proof (as 

 imaginary as the roots to which it refers), and that he would 

 listen with some pleasure to a sober exposition of a subject which 

 had so deeply engaged his thoughts*. I am sorry that a dif- 



* The delusion appears to have assumed the chronic form which is usu- 

 ally confined to quadraturists of the circle, inventors of perpetual motion, 

 and the oppugners of the received laws of falling bodies. It is my rule 



