﻿Skey, — Electro-motive Power of Gold and Platina in Sulpliides. 313 



In the case of the silver ore, however, this variation may be clue to a 

 difference in molecular arrangement, as sulphide of mercury, though a non- 

 conductor in the state of cinnabar (red variety), conducts freely when its 

 precipitate is simply dried or sublimed, so long as it retains its dark colour. 



Several other interesting questions are started by the knowledge of some of 

 the facts above disclosed ; for instance, the conducting power of native oxide 

 of zinc for electricity is remarkable ; the specimen tested, I may state, being 

 neai-ly pui'e, and of a reddish colour. Possibly this circumstance (that of its 

 conductivity) tends to show that it is rather a mixture of a higher oxide with 

 the protoxide than a simple protoxide as now supposed. 



Why some sulphides conduct so readily, and others do not conduct to any 

 notable extent, is another most imj)ortant question in physics, and one which 

 the results above stated are too few in number and not sufficiently varied in 

 kind to enable us to solve. I firmly believe, however, that when they are 

 checked and largely added to by results of experiments upon larger mineralogical 

 collections than the one to which I have had access, and especially upon minerals 

 prepared chemically pure, and in different allotropic states, the question raised 

 above, and othei-s allied thereto, will receive their proper answers, and electrical 

 science be enlarged. 



I -may state in conclusion that I have frequently found the testing of 

 imknown ores in regai'd to their electric conductivity a very useful pre- 

 liminary to their chemical investigation or analysis. It is a test easy of 

 application, and does not of course necessitate breaking up or damaging them 

 in any way. 



Art. LII. — On the Electro-motive and Electrolytic Phenomena developed hij 

 Gold and Platina i?i Solutions of the Alkaline Sulphides. By W. Skey, 

 Analyst to the Geological Survey of JSTew Zealand. 



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



In some former papers upon the absorption of sulphur by gold and platinum* 

 I adduced evidence to show that this absorj)tion was a chemical act ; that a 

 true chemical combination had been effected between the sulphur and the gold 

 or platinum, as the case might be, the result being a sulphide of the metal 

 used ; and I stated that, so far as this evidence could be deemed woi-thy of 

 acceptance, it impugned the correctness of the general belief that the absorp- 

 tion of certain gases by platinum was in every instance simply mechanical. 



Irrespective, therefore, of the primary question raised, it became of some 

 importance, upon general grounds, to obtain further and, if possible, decisive 



* See Trans. N. Z. Inst., Vol. III., pp. 216 and 221. 



