﻿312 Transactions — Chemistry. 



placed on a flat sui-face of them, at the same distance from each other as before 

 used. 



When a solid had to be compared with a liquid the ends of the wires were 

 allowed to be well under the surface of the latter, the same distance being 

 maintained between the wires as before. It was afterwards found, however, 

 that their immersion to a considerable depth did not materially affect the 

 reading of the instrument. 



_ In the annexed table the results of these experiments are embodied ; those 

 substances which have proved the best conductors by this process being placed 

 superiorly. All the ores were selected for compactness and purity, and were 

 mostly crystallized. 



Mispickel Binoxide of manganese 



Galena Iron pyrites 



Sub-sulphide of copper Kitric acid (concentrated) 



Ferro-sulphide of copper Per-chloride of iron (concentrated) 



Profco-sulphide of iron Sulphuric acid (concentrated) 



Tin pyrites Sulphuric acid (weak) 



Nickel pyrites Sea water 



Sulphide of bismuth Titanic iron 



Magnetic iron ore Boulangerite 



Oxide of zinc Hematite (impure) 



Graphic tellurium 

 The following minerals were proved to be non-conductors or comparative 

 non-conductors : — Sulphides of molybdenum, zinc, antimony and manganese ; 

 cinnabar (red variety, ciyst.), orpiment, boiirnonite (cryst.), proustite, pyrargy- 

 rite, silver glance, carbonate of iron (black variety, cryst.), chrome ore (cryst.), 

 wolfram (cryst.), specular iron ore (cryst.), rutile, braunite, tin ore (cryst), 

 leverite (cryst.), sub-oxide, and protoxide of copper, iserine, oxychloride of 

 copper. 



The table above given discloses the fact that a gi'eat number of our oi-es 

 are superior in conducting power for electricity to the best liquid non-metallic 

 conductors we are at present acquainted with ; indeed, most of the minerals 

 which fall in this class are by approximate admeasurements very far superior 

 in this respect to such liquids. 



I should state that all the minerals cited here are native ores. 

 All the ores of silver named above were found to be more or less anti- 

 monial, from which circumstance their refusal to conduct electricity may be 

 due, as the pure sulphide, chemically prepared and fused, conducts very well. 

 The effect of antimony in impairing conductive power is well exemplified 

 in the case of bournonite and boulangerite, as compared with the non- 

 antimouial lead ore, galena. 



