170 Mr. J. Cockle on the Method of Symmetric Products. 

 hydride of sethyle, 



SriSnO^-Snl. 



Both these causes probably contribute to produce the excess 

 of hydride of sethyle ; but the very small amount of gaseous 

 products, compared with the solid ones, convinced me that the 

 production of the former is only an accidental circumstance, 

 which, however it may be interpreted, does not at all aflfect the 

 principal reaction, viz. the formation of iodide of stanaethyliura. 

 The gases, evolved by the action of light upon iodide of aethyle and 

 tin, are perfectly similar to those obtained by the action of heat. 



Stanmethylium and stanamylium are formed when the iodides 

 of methyle and amyle respectively are exposed to the action of 

 light in contact with tin ; their salts are isomorphous with those 

 of stansethylium ; but I have not yet completed the investigation 

 of these bodies. 



[To be continued.] 



XXVII. On the Method of Symmetric Products. By James 

 Cockle, M.A., of Trinity College, Cambridge; Barrister-at- 

 Law of the Middle Temple^. 



[Continued from vol. iv. p. 496.] 

 17. nPHE following processes, which supersede the formidable 

 J- eliminations threatened by the conditions already 

 arrived at, appear to suggest a general method of treating sym- 

 metrical equations. 



18. From the terms in y<^ y^ and y^ y^ respectively we obtain 



t . /5~S . «,a2«3/34=0 and 2 . P,P^-X . a,u^^^P^=0, 

 or 



and 



19. It follows from this that 



(/3, + ^5) (E -^, -^5) = K^i + «, ft) (E - «5^, -a.ft), 

 and we find 



^l+^2 = a2A + «1^2 01' «4/^3 + «3A> 

 /^3-i-/^4 = «4/Q3 + a3^4 or «2^1 + «l/32- 



Of these systems of values I, here at least, adopt the former and 

 make 



^l + /32 = «2/5l+«l/52, ^3 + 134 = ^41^3 + ^sl^A, 



* Communicated by the Author. 



