402 Scientific Intelligence. Geology. 



he had extracted from the latter the silver which it contained, 

 under the form of crystals. The minerals on which the experi- 

 ments were made were the ores raised in Columbia and the ore 

 of Allemont. The same method has also been successfully em- 

 ployed to extract from the copper-pyrites of Chessy, near Lyons, 

 the silver which it contains, without affecting the copper. It is 

 only from the argentiferous galenas that it is difficult to extract 

 the silver. When a mineral like that of Allemont contains many 

 metals, as lead, copper, &c., each of these metals is separately 

 reduced, and at different times, so that the separation is easily 

 affected. From this it results that the ores of lead and copper 

 may be treated in the same manner as those of silver, but with 

 much less facility, because of the different degrees of oxidation 

 which they acquire, and the compounds which they form during 

 roasting. M. Becquerel is at present occupied with further re- 

 searches on the extraction of metals, but deemed it proper, for 

 the interest of science, to make known to the Academy the prin- 

 ciples by means of which he has been able to extract some metals, 

 particularly silver, from their respective ores. 



19. On the Results of Mr Fox's Experiments on the pro- 

 duction of Artificial Crystals by voltaic action. We have al- 

 luded, in page 83 of the last number of this Journal, in refe- 

 rence to a paper by M. Becquerel, in the third part of the 

 " Scientific Memoirs," to the communications of Mr Fox and 

 Mr Crosse, at the Bristol Meeting of the British Association 

 relative to the production of artificial crystals by voltaic action. 

 We are now enabled, by the kindness of Mr Fox, in sending 

 specimens of the altered ores for examination, to give a more 

 exact account of the results of his experiments than we could 

 otherwise have done. Mr Fox's own statement is as follows : 

 " The experiment referred to was performed in the follow- 

 ing manner : An earthenware trough was divided by a parti- 

 tion of moistened clay into cells, into one of which was put a 

 piece of the yellow sulphuret of copper, the cell being filled 

 with a solution of the sulphate of copper, and into the other a 

 piece of zinc, and the cell filled with water, either pure or slight-r 

 ly acidulated by sulphuric acid. The zinc was then connected 

 with the copper-ore by means of a copper wire passing over the 

 wall of clay. This simple voltaic arrangement soon rendered 



