Mr. G. B. Jerrard on a Method of Transforming Equations, 493 



alloy, that is, the pickling. Copper is rolled when at a red heat, 

 and in this operation it becomes covered with a black scale of 

 oxide, which adheres firmly to the surface. This is removed by 

 moistening the surface with urine, then making the sheet red- 

 hot and plunging it immediately into water, when the oxide 

 scales ofi"; this operation is termed pickling. Some qualities of 

 copper part with this scale with great difficulty ; large portions 

 adhere, and can only be imperfectly removed by rubbing, which 

 affects the value of the sheet of metal. We have seen copper of 

 the purest quality pickle so bad as to affect its sale. It is very 

 probable that a little alloy, if not altogether essential, greatly 

 assists this operation. Lead and tin prevent; arsenic, anti- 

 mony, and silver assist pickling, circumstances which suggest 

 the probability of the cause being electrical ; as those metals 

 which are positive to copper prevent pickling, and those that are 

 negative to it in the ielectrical scale assist. 



We have in these papers given a brief detail of the processes 

 at present in use for manufacturing copper from its ores, and 

 traced, so far as our experience enabled us, the various chemical 

 changes which take place. A great variety of improvements 

 have been proposed and patented for copper smelting. A few of 

 these are worth a trial, and bid fair to be of use ; but the greater 

 portion of them exhibits a want of practical knowledge of the 

 processes adopted, and consequently the requirements of the 

 trade. The merits or otherwise of these processes it is not our 

 present intention to review ; but we hope that these papers will 

 supply a desideratum, and enable those who are not in the trade to 

 appreciate the difficulties experiencedby those who areengagedinit. 



LXXVIII. On a Method of Transforming Equations by means 



of Symmetric Functions. By G. B. Jerrard. 



[Continued from p. 363.] 



8. TN the solution of Problem I., when \=3, it is implied 



A that the six equations 



will obtain at once in virtue of the condition 

 so that the first members of the equations 



.. 2Bj ., 2% .4 . 2^6 ^ 



