formation op coal and carbonaceous minerals. 125 



Note 3. — on kernel roasting. 



Tlie plieiiomenoii of " kernel " roasting is well known to all 

 metallurgists, hut it does not appear to have been recorded 

 whether silver follows the copper into the kernels. 



During the open-air roasting of very large quantities of 

 sulphides, consisting of intimate mixtures of pyrites, copper 

 pyrites, blende and galena, careful watch was kept for good 

 kernels. These were not very plentiful, the galena and blende 

 apparently preventing their formation. 



However, a number of good kernels of varying sizes were 

 collected, and, the separation in most cases being imperfect, all 

 the kernels were mixed together, and all the shells, and assays 

 carefully made of the average. The result was : — 



Kernels | ^^1^'^^'' ^l.^f' ^ ^^^^J- P^'" *«"• 

 ( Uopper, [6.1 per cent. 



q / Silver, 20 ozs. 8 dwts. per ton. 



) Copper, 2.7 per cent, 

 which proves that silver does concentrate in the kernels but to a 

 less mai'ked extent than copper. 



[Drs. Rennie, Leibius, and Messrs. J. A. Pond and W. M. 

 Hamlet took part in the discussion on these papers.] 



Thursday, August 30th. 



The President, Mr. J. G. Black, M.A., DSc, Professor of Chemistry 

 and Mineralogy, University of Otago, New Zealand, in the Chair. 



The President delivered an addre:ss " On Chemistry in relation to 

 Education." 



The following papers were read : — 

 l._SOME CONSIDERATIONS IN REGARD TO THE 

 FORMATION OF COAL AND CARRONACEOUS 

 MINERALS. 



By W. a. Dixon, F.I.C, F.C.S., Lecturer on Chemistry, Sydney 

 Technical College. 



In most chemical manuals the production of coal, and similar 

 carbonaceous minerals, from cellulose is assumed and equations are 

 given shewing its transformation into coal, of difterent varieties, by 

 the elimination of oxygen and hydrogen as water, carbon and 

 oxygen as carbon dioxide, and carbon and hydrogen as methane. 

 These are known to be evolved during the decomposition of 

 vegetable matter and are assumed to be given oft" by cellulose, and 

 as this has a high molecular weight and as any acquired number 



