1851.] Report on the Copper ores of the Beoghur Mines. 11 



these ores contain, and by which only they can be wrought to profit,* 

 and having obtained a supply, though rather limited in quantity, I 

 first most carefully picked and sorted the ores, and obtained a pound 

 troy weight of two of them, from which the following experiments 

 were made, after some preliminary trials of which it is unnecessary here 

 to give particulars ; being, though tedious, only those which all labora- 

 tory work requires before an experiment for publication is made. 

 Amalgamation I. 

 The first was the ore F. a bright brick-red Pacos. 



One pound troy was carefully reduced to a fine powder, and salt 

 and magistral^ added, in larger proportions than usual on the large 

 scale, in a large mortar, and on subsequent days the mercury was duly 

 added, but also in larger proportions, to insure the successful extrac- 

 tion of all the silver. 



The mass was worked over every two days by the pestle, and kept 

 at the proper degree of moisture. On the twenty-fourth day it was 

 carefully washed off, and the mercury driven off by heat ; and though 

 there was some small loss from ebullition of the mercury in the cruci- 

 ble, and some also in washing such small quantities, as I ascertained by 

 experiment, yet I had the satisfaction of obtaining 5 grs. of pure silver 

 from the pound troy ; which for the Caxon of 5000 pounds Avoirdu- 

 pois would give somewhat better than 8^ marcs of silver to the Caxon ; 

 and ores are sometimes wrought in Mexico and Peru of 2 and 2\ marcs 

 when quicksilver is cheap : Ores which give above six marcs being 

 called good metal. The highest specimen we have in the museum is 

 marked as giving 500 marcs and the lowest 20 ; but all those so 

 valued are sulphurets ; none of the Pacos , unfortunately, are valued. 

 Amalgamation, No. II. 



The second trial by amalgamation was with the specimen D, the 

 dark liver-coloured Fahlerz, the only one, besides the above, of which 

 I could obtain a troy pound weight. The process was of course the 

 same, but, though the weather was cooler, only 20 days were allowed 



* All attempts to introduce the German and other amalgamation processes in 

 Mexico have been failures with the poorer ores which form the riches of the great 

 Mexican mines ; and this error was in great part the ruin of the Mining Companies 

 from England. 



f Roasted sulphuret of Copper. 



c 2 



