130 Mr. J. Cockle on the Method of Symmetric Pi'oducts. 



Exp. XX. Sample purchased at Messrs. Blundell^ Spence and 

 Co., 9 Upper Thames Street, as Pattinson's genuine oxychloride 

 of lead. Reduced 3 lbs. troy in the same way as Exp. XIX. Of 

 the lead obtained, cupelled 4000 grs. ; the small button of silver 

 obtained, parted by nitric acid, left a very minute trace of gold. 



Exp. XXI. Repeated Exp. XX. on 4000 grs. of lead; treated 

 the button of silver left by cupellation with nitric acid, and a 

 vei'y minute trace of gold was obtained. 



Acetate of Lead. 



Exp. XXII. Sample purchased at Mr. C. Button's, Holborn 

 Bars, slightly coloured with oxide of iron. 2 lbs. troy (11,520 

 grs.) reduced by projecting it in small quantities at a time into 

 a hot Cornish crucible, and finally heating until all the lead was 

 separated ; lead obtained weighed 5700 grs. 2000 grs. of this 

 lead, cupelled, did not leave any visible trace of silver. 



Exp. XXIII. Repeated Exp. XXII. upon 3000 grs., but no 

 button of silver was obtained. 



Exp. XXIV. Repeated Exp. XXII. Took of acetate of lead 

 2 lbs. troy (11,520 grs.) and reduced it by heating in a Cornish 

 crucible ; lead obtained weighed 5860 grs. 4000 grs. of this 

 lead cupelled to about 200 grs. on a large cupel ; it was then 

 transferred to a small cupel and the operation completed; a very 

 minute globule of silver remained, which was treated with nitric 

 acid, and a just perceptible trace of (jold was obtained. 



Exp. XXV. Sample bought at Mr. H. Barnes's, 38 Long 

 Acre (very white and clean). 5760 grs. reduced by heating in 

 a Cornish crucible, gave of lead 3136 grs. Of this lead, cupelled 

 2000 grs., obtained a very minute globule of silvei", which by 

 parting with nitric acid left a. just pierceptible trace of gold. 



Exp. XXVI. Repeated Exp. XXV. 5760 grs. reduced as 

 before, gave of lead 2830 grs. Of this lead, 2000 grs. cupelled 

 gave a very minute globule of silver, which, after parting with 

 nitric acid, left o. just perceptible trace of gold. 



[To be continued.] 



XIX. On the Method of Symmetric Products. By James Cockle, 

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

 Middle Temple"^. 



[Concluded from vol. v. p. 174.] 

 44. /QUADRATICS furnish us with a function which, if not 

 V^lU the strict analogue of those presented by the other 

 equations, may yet be considered as corresponding to them. 



* Communicated by the Author. 



I 



