292 



the saving of and the extraction of gold from the pyrites. The principles of 

 the process are — 



" 1st. Concentx-atiou of the ore. 



" 2nd. The roasting-sweet, or until all the sulphur has been drawn off, and 

 oxides only remain. 



" 3rd. The amalgamation of the roasted mass in a semi-moist state by 

 trituration, and the collection of the finely divided amalgam by means of an 

 additional lai^ge amount of quicksilver and water, and ultimate washing off. 

 The saving and concentration of the pyrites is the most difficult operation, on 

 account of the slight difference in specific gravity between the material to be 

 saved and the quartz and other associated earthy matter. It has, however," 

 Mr. Daintree observed, " been accomplished with tolerable success by Mundy's 

 Patent Buddie, Stanfield's Patent Concentrator, and Thompson's Patent 

 Percussion Table. Mr. Ulrich also recommends, as more perfect for this 

 purpose, the Self- Acting Hydraulic Digging Machine, which he saw at work 

 in the Hartz Mountains, and in the principal disti'icts in Germany." 



The roasting of the ore is effected in large reverberatory furnaces. One 

 with sjiecial ari-angements for this kind of work, patented by Mr. Lata, in use 

 at the Port Phillip Company, at Clunes, is highly recommended. 



Por accomplishing the third operation, an "arrastres" is employed. Great 

 care should be taken that for the trituration with quicksilver the stuff is not 

 too moist. 



With regard to saving the fine free gold generally associated with pyrites, 

 and of which, on the latter account, there is no doubt a large amount lost in 

 the tailing ; Mr. Ulrich recommends the Tyrolese gold mills, which, on a recent 

 visit to Eui'ope, he saw at work in the celebrated gold and silver mining 

 districts of Schemnitz, in Upper Hungary. These mills, which require but little 

 attention and power to work, save gold too fine to.be seen with the naked eye, 

 from an ore composed of galena and iron, and copper pyrites, and are successful 

 with even so little as two to three dwts. per ton. 



I have brought this subject before the notice of the Association in rather a 

 loose and unconnected form ; but as the attention of prospecting parties has 

 lately been turned to the Maitai Yalley and neighbouring country in search of 

 gold, I have some hopes that the facts and somewhat new features which exhibit 

 themselves in the gold-mining districts of a neighbouring colony, under 

 features almost identical with our own district, may be of some use in directing 

 the search. 



[In consequence of remarks in the above paper, both the cupreous and 

 chromic iron ores from the Dun Mountain were analyzed, and in both, distinct, 

 though small, quantities of gold were detected. From 120 grains of the 

 former, the amount obtained is visible to the unaided eye. — J. Hector.] 



