﻿Skey. — Conducting Poioer of Metallic Sulphides and Oxides. 311 



lY.— CHEMISTRY. 



Art. LI. — On the Conducting Power of various Metallic Sulphides and Oxides 

 for Electricity, as compared with that of Acids and Saline Solutions. By 

 William Skey, Analyst to tlie Geological Survey of New Zealand.* 



[Read before the Wellington Philosophical Society, 2Qth January, 1871.] 



In papers read before this Society last year,t I showed that the metallic sul- 

 phides and arsenides generally were capable of exhibiting strong electro-motive 

 power when paired either among themselves or with metals electrically 

 negative to them, from which circumstance it appears that their capacity to 

 conduct electricity is greater and more general than is at present contemplated 

 for them. 



It therefore became a matter of some interest to ascertain what are the 

 exceptions to this general electric conductivity on the part of these minerals, 

 and also to compare those which do conduct electricity with our best conduct- 

 ing solutions of acids or salts ; the very low electric conductivity asssigned to 

 even the best conductors among these ores in our most recent works on elec- 

 tricity, and the fact that they are all placed in these works (under one head 

 ing, that of " oi-es") below the feeblest liquid saline conductors, when coupled 

 with that of their general conductivity, made it especially desirable that a 

 strict comparison should be instituted between the minerals and saline solu- 

 tions referred to, in respect to their relative conducting power for electricity ; 

 and I have therefore attempted this in the manner below described. 



I had hoped to furnish absolute results, but the time at my disposal, and 

 my inability to possess myself of a sufficiently delicate resistance coil, has 

 limited me for the present to seeking only after relative results. 



The following is the method I employed : — 



A voltaic cell of constant power was connected with a galvanometer, and 

 this with platina wire electrodes of equal diameter, the free ends of which were 

 ground plane, and fixed at a determinate distance from each other. In the 

 case of testing liquids the wires were immersed in them to a uniform depth, 

 and the indications, when they had attained constancy, were read off vipon 

 the galvanometer. In the case of solids the ends of the wires were firmly 



* [This and the following Chemical Papers have been revised for the press by the 



Author. — Ed.] 

 + See Tram. N. Z. Inst., Vol. III., p.p. 222 and 232. 



