156 PROCEEDINGS OF SECTION B. 



As already stated, gold deposited by organic matters is filmy 

 -cr finely granular, the tendency of such an agency being the 

 same as that of the ferrous salts, namely, to disperse in grains 

 rather than aggregate in masses, and it appears certain that to 

 whatever extent the auriferous deposit had formed therein, a 

 vegetable structure would be apparent in the metallic mass. As 

 little of our gold has this structure, but little of it could have 

 been formed in this way. If, however, organic matters have not 

 been the nuclei for gold, they might still be the main reducers 

 of gold from its solutions, and to other substances we must look 

 for the nuclei to aggregate the gold so reduced. 



Impressed with this idea, and by facts respecting the differences 

 in composition of reef and alluvial gold, Dr. A. R. C. Selwyn, 

 now Director-General of the Geological Survey of Canada, 

 proposed the following theory : — 



" That nuggets may be formed and that particles of gold may 

 increase in size through the deposition of metallic gold from the 

 meteoric waters percolating the drifts, and which must have been 

 during the time of our extensive basaltic ei'uptions of a thermal 

 and probably highly saline character favourable to their carrying 

 gold in solution." 



The means by which the gold was to be precipitated from these 

 solutions is not stated, except it be inferred that the nuclei were 

 to perform this ofiice also. However, the late Mr. R. Daintree came 

 forward to assist the theory of Dr. Selwyn, with a description 

 of certain phenomena he had observed, showing according to his 

 interpretation, that a fragment of gold is a nucleus to itself as 

 deposited Jrom a solution of its chloride hy organic matter. 



As this had a new and important bearing on the question as to 

 how gold nuggets have been formed, I attempted at the time to 

 reproduce Mr. Daintree's results in the laboratory. For this 

 purpose experiments were made by taking a curved disc of thinly 

 hammered gold of known weight, and placing the same in gold 

 solution under varying conditions. 



In the first experiment, pieces of cork and glass were employed 

 as nuclei, light being excluded, and the gold deposited found by 

 simple weighing. 



The quantity deposited upon the gold disc was found by 

 numerical calculation to be not more, in proportion, relatively to 

 the surface of a disc, than that which the remainder of the gold 

 bore to the extent of the surfaces upon which it had affixed itself. 



Second. — The same experiment repeated, but vessel and 

 contents not darkened. 



Third. — Gold solution reduced to half its strength. Difiused 

 sunlight admitted. 



Fourth. — Soluble organic matter used in place of wood ; sun- 

 liifht excluded. 



