58 



EIGHTH REPORT — 1838. 



he considered these results would go far to support or refute the opi- 

 nions he had hazarded on this subject. 



The results of these experiments were uniform ; they differed from 

 Dr. Bird's in one remarkable circumstance, viz. that the copper, instead 

 of being deposited in a crystalline form, was in nodular or tubercular 

 masses (a specimen was exhibited to the Section). When the plaster of 

 Paris diaphragm, which of course was vertical, was carefully made, and 

 one side of ajar thus divided was filled with water, and the other with 

 a solution of sulphate of copper, no intermixture of fluids was evident 

 even at the end of a month. On placing in the solution of sulphate 

 of copper, at a certain distance from the vertical partition, a mass of 

 copper pyrites, connected by a copper ribbon with a piece of zinc im? 

 mersed in the water in the other cell, voltaic action slowly commenced. 

 At the end of a few days the water in the zinc cell became acid, bub- 

 bles of hydrogen gradually appeared, and were slowly evolved, whilst 

 the copper pyrites slowly assumed the iridescent appearance of peacock- 

 ore described by Mr. Fox : in a month the apparatus was dismounted ; 

 no trace of sulphate of copper was found in the water cell, and neither 

 the zinc nor the mass of pyrites had touched the plaster diaphragm. 

 On removing the latter, a copious deposition of firmly adherent me- 

 tallic copper, in a nodular or almost stalagmitic form, was found on that 

 surface Avhich had been exposed to the metallic solution ; and, on 

 breaking the mass of plaster transversely, numerous delicate veins of 

 copper appeared permeating it in every direction. This experiment is 

 considered by Dr. Bird to be less liable to sources of fallacy, and 

 much less exceptionable than those described by him last year ; for, 

 not only is all metallic contact with the plaster diaphragm carefully 

 avoided, but the very form of the reduced copper would afford an ar- 

 gument against its being furnished by portions shooting off from the 

 negative electrode, on the beautifully iridescent surface of which, 

 moreover, no trace of reduced copper liad appeared. 



Arrangement of the Apparatus. 



A is a conical earthen vessel, in which the 

 plaster diaphragm B is carefully fitted. 

 C. The cell filled with water, and contain- 

 ing a piece of zinc metallically connected with 

 a mass of native copper pyrites, placed in the 

 cell D, which is filled with a solution of sul- 

 phate of copper. On the surface of B, where 

 the irregularities E are sketched, is the cop- 

 per deposited in a nodular form, and con- 

 nected apparently with delicate metallic veins 

 traversing B in every direction. 



