REPORT OF DEPARTMENT OF JIETALLURGY. 251 



that of any other metal. No illustrations of the process of extracting 

 silver directly from its ores by stamping and amalgamating were ob- 

 tained. This is a ])rocess that is of somewhat limited application and 

 jet one of considerable importance, so that a collection illustrating it 

 would be very desirable. 



The treatment of base ores, that is, ores carrying lead and silver, by 

 roasting with salt (chloridizing) and stamping and amalgamating, is 

 illustrated by three collections made by the curator. The first collection 

 is from the Ontario Mill, Park City, Summit County, Utah, which works 

 the ore from the Ontario Mine and uses the Stetefeldt furnace for roast- 

 ing. This is a souiewhat remarkable mine on account of the persist- 

 ency of the vein and its richness, but more especially on account of the 

 large amount of water which has to be contended with. As much as» 

 6,000 gallons are discharged from the mine per minute. This collection 

 includes a very full series of the ores taken from different parts of the 

 mine, selected by Captain Keith ; several average samples of the ore as 

 delivered to the mill ; the dried ore; the stamped ore; the salt in himps, 

 dried and crushed; the mixture of the ore and salt ready for the roast- 

 ing furnace; the roasted ore taken from the bottom of the stack ; the 

 roasted ore taken from the return flue, and samples taken from each one 

 of the twelve dust chambers; the amalgam produced by treating the 

 roasted ore in pans with mercury; the base bullion produced from re- 

 torting the amalgam, which is from COO to 800 fine ; and the tailings as 

 discharged from the mill. In making this collection the curator was 

 assisted very materially by Mr. Joseph Gallagher, the superintendent of 

 the mill, and the Museum is much indebted to Mr. R. C. Chambers, the 

 general manager of the company, for the facilities cheerfully afforded 

 in making this collection. Two collections were also made by the cura- 

 tor at Butte, Mont., representing the same process. The series of 

 specimens are essentially the same as that from Park City, but the 

 course of operation is somewhat diftereut, owing to the different char- 

 acter of the ores. At the Moulton Mill, where every attention was 

 shown the curator by Mr. J. K. Clark, the manager, the ores are dried 

 on plates and roasted in a Howells revolving cylinder. Besides the 

 hard unaltered ores of the Moulton Mine this mill works a considerable 

 amount of custom ore from many different outlying mines, especially 

 the soft surface ores which have undergone a great deal of alteration. 

 At the Lexington Mill, which works only the ores of the Lexington 

 Mine, the ores are dried in a Stetefeldt shelf-drier and roasted in a 

 Stetefeldt furnace. 



In the extraction of silver by smelting it has been quite difficult 

 to get a thoroughly satisfactory collection, on account of the reticence 

 of the manufacturers as to details of the process, and also their unwill- 

 ingness to allow specimens to be taken. A fairly complete collec- 

 tion representing the smelting of the argentiferous lead ore and the 

 refining of the base bullion (silver and lead), at a works having at com- 

 mand a large variety of ores, was obtained from the Cheltenham Works, 



