198 ELECTROLYSIS. 



at Marseilles, by the Oker Foundry in Saxony, by the mines of 

 Mansfeld, by Messrs. Lyon-Allemand at Paris, by M. Andre 

 at Frankfort, &c., and by a few large English manufacturers, 

 notably Messrs. Elkington, and Elliott, of Selly Oak, near 

 Birmingham. 



HAMBURG REFINING WORKS. All refined coppers are not 

 equally good conductors of electricity ; their degree of purity, 

 and consequently of conductivity, is dependent on the nature 

 of the metal submitted to the electrolytic operation and on 

 the conduct of the operation. The copper which has the best 

 reputation is that manufactured under the direction and on 

 the system of Dr. Wohlwill, by the Norddeutsche Affinerie 

 of Hamburg. The current in this factory is obtained from 

 six Gramme machines, No. 1 type, and also from a much 

 more powerful machine specially constructed for M. Wohlwill 

 in 1873. 



The admittance of the public to the works of the Nord- 

 deutsche Affinerie is prohibited, so that we have not been able 

 to obtain precise information as regards all the processes in use 

 at Hamburg ; we will describe further on the principal features 

 of the electric installation, but we can already assert that in 

 our opinion there is no manufacturing secret. M. Wohlwill is 

 an intelligent chemist, well - informed in all the questions 

 relating to electricity ; he does not leave anything to the 

 unforeseen ; his baths are prepared with care, and always 

 maintained at the same temperature and the same degree of 

 concentration ; his machines revolve at regular speeds, and are 

 always in perfect working order; his coppers are minutely 

 analysed both before and after the operation ; in short, installa- 

 tion, current, bath, manipulations, &c., everything contribute 

 towards a satisfactory result. This is the sole reason of the 

 superiority of the coppers produced by the Norddeutsche 

 Affinerie. 



The daily production of this manufactory reaches 2 tons 

 (2500 kilogrammes) of chemically pure copper. The treated 

 copper often contains precious metals, which are found in the 

 bath after the opei\ation. The quantity of fine gold gathered 

 at Hamburg in 1880\reached as much as 1200 kilogrammes. 



