I I 2 JOUENAL OF SCIENCE. 



education has been obtained in a small school, and unless he possesses 

 rare intelligence his knowledge will be correspondingly narrow. It 

 would not be difficult to give you many examples of this from that 

 most conservative of English counties — Cornwall. From the younger 

 miners tb^re one bears continually the observation : We are 20 years 

 behind the Americans in mining methods. Yet the Cornish miner, as 

 an individual, is not surpassed by any other miner in the world. One 

 could not point to better examples for illustrating this than those which 

 can be seen or read of in the United States. Disregarding these, 

 however, for the moment, I should like to give you two examples 

 which are now historical. For' the appreciation of our first example it 

 is necessary to understand how gold occurs in the lodes from which it 

 can be economically extracted. Gold may be said to occur in two 

 conditions — first, as a native metal; and, second, in intimate com- 

 bination with other metallic compounds. When found native, gold 

 readily alloys with mercury, forming an amalgam. Advantage is taken 

 of this fact in the ordinary separation of gold from its veinstuff. In 

 this case mercury is used as a collecting agent, as owing to its affinity 

 for gold it readily absorbs any line particles which are brought into 

 contact with it. When sufficiently saturated, the mercury with the 

 alloyed gold is collected, placed in a retort and heated. By this 

 treatment the mercury is distilled from the gold and can be used again 

 for the same . purpose. Thus its extraction is comparatively simple. 

 The only important question being how much there is of it. But when 

 gold occurs in combination with metallic compounds like ordinary 

 mundic, it will not readily alloy itself with mercury, and the ordinary 

 treatment fails to extract it. The cause of this failure does not seem to 

 have been fully recognised until one of those patient and ingenious 

 men, known as German professors, not only saw the reason of this 

 difficulty, but completely surmounted it. The substance in which gold 

 is most generally found in this obstreperous condition is a compound of 

 iron and sulphur. Now, Plattner reasoned thus : Either the gold is in 

 some form of chemical combination with the sulphur of the pyrites, or 

 it occurs as plates of almost infinitesimal thickness between the 

 crystalline plates of the mineral. In other words, it is occluded by the 

 mineral. Whatever the condition may be, the crystalline character of 

 the mundic will be destroyed by roasting it, and so the gold will be 

 liberated. Then possibly one may be able to extract the gold with 

 mercury. But here a new difficulty is found. By roasting this 

 mundic, an oxide of iron is formed, and it is found that this iron oxide 

 has a deleterious effect on the mercury. In gold-mining phraseology, it 

 " sickens " it. Thus it was necessary to tack about for a new method, 

 and finally he hit upon the plan of treating this refractory gold with 

 chlorine and then dissolving the chlorinated gold in water. By these 

 means Plattner first solved the economical extraction of ore from 

 pyrites. His plan has been largely adopted in America and Australia, 

 and is now the source of considerable profit to gold mining companies. 

 The Mount Morgan ore is, I believe, entirely treated by this process. 

 May I ask your attention while I give you another example of this 

 adaptability, one that has exerted a tremendous influence upon a still 

 more important industry. At the British Association meeting in 1865, 

 Sir H. Bessemer announced, amid considerable surprise and constei - - 



