124 



PROCEEDINGS OF SECTION B. 



The samples were taken hot in the usual manner at frequent 

 intervals ; each assay represents eight hours work ; the slags for 

 twenty-four hours were sampled next day in bulk when cold, care 

 being taken to secure only " clean " specimens. 



These assays seemed conclusive, but for confimation some pots 

 of slag, also containing matte, were sampled hot, then placed 

 aside to cool, and samples taken again when cold. The result 

 given in the next table, while to a certain extent confirmatory, 

 was not altogether satisfactory. 



No opportunity occurred for making other experiments but 

 upon retreating the rich slags their average silver contents were 

 found to be 6 ozs. 5 dwts. per ton, against a general average for 

 the run, according to the ordinary system of hot sampling, of 3 

 ozs. 4 dwts. per ton. 



Note 2. — on the distribution of silver in iron and copper 



MATTES. 



In Percy's " Metallurgy " (Silver and Gold, Part I., p. 509) 

 it is stated that, in the process thei'e described, the last liquid 

 portion of the matte is found to be richer in silver than 

 the removed solid cakes. The writer has recently had occasion 

 to run large quantities of matte into moulds, and has noticed 

 that upon breaking the blocks when cold, a curious cannon-ball 

 like mass of a crystalline character separates from the outer part 

 which comes off like a shell. These cores upon assay are found 

 to contain a much larger proportion of silver and copper than the 

 shells, and the accurate sampling of large parcels of matte has 

 been a matter of considerable difficulty owing to this cause. The 

 following assays shew the diffierence in value : — 



