Tension of Minerals, 339 



Melted galena. 



" Spiegeleisen." 



Meteoric iron (Aix-la-Chapelle). 



Alloy of antimony and copper. 



Graphite, No. 1 (very compact; used for the electric light). 



Melted magnetic pyrites. 



Cobalt pyrites (Miissen near Siegen). 



Native arsenic. 



Nickel glance (Ems, Nassau). 



Antimony. 



Magnetic pyrites. 



Melted copper glance, No. 1. 



Sulphuretof iron (for the preparation of sulphuretted hydrogen). 



Melted iron pyrites, No. 1. 



Copper glance, No. 1 (two specimens from the same locality). 



Alloy of two parts antimony and one part zinc. 



Graphite, No. 2 (native). 



Subsulphide of copper, No. 1. 



Copper glance, No. 2 (Cornwall). 



Subsulphide of copper, No. 2. 



Cobalt glance. 



Tellurium, No. 1 (chemically pure). 



Tellurium, No. 2 (prepared by Professor von Liebig). 



Arsenical pyrites. 



Fahlun ore, No. 1. 



Fahlun ore, No. 2 (small specimen). 



Copper glance, No. 3 (Bristol County, America. Four 



specimens from the same locality examined). 

 Fahlun ore, No. 2 (larger piece from the same locality). 

 Melted copper glance, No. 3. 



For those substances which lie beyond bismuth on the one 

 side and antimony on the other, I employed, with scarcely an 

 exception, a galvanometer with a great number of coils of thin 

 wire ; whilst for those minerals which are situated between the 

 above-mentioned metals, it was necessary to use an instrument 

 with only a few coils of thicker wire. 



Besides those mentioned in the above series, many other 

 minerals were tested without yielding any noteworthy results. 

 Although pyrolusite, manganite, and Braunite are mentioned 

 above, Hausmannite gave no current. Amongst ores containing 

 iron, specular iron ore, brown iron ore, chrome iron ore, spathic 

 iron ore, and Lievrite caused no deflection of the needle. Zinc- 

 blende was also tested, but it did not conduct electricity. Other 

 ores, again, such as those containing the sulphides of antimony 

 and silver, were precluded by reason of their easy fusibility. 



Z2 



