364 TKAN8ACTI0NS OF THE CANADIAN INSTITUTE. [VOL. IV, 



for five or six (5 or 6) hours, the cloth is converted into a tinder and 

 afterwards scraped off the cullender by a brass brush. 



In 1790 the "Freiberg," or "Barrel process," of amalgamation was 

 introduced at Halsbriicke, near Freiberg, in Germany. The ore con- 

 tained, beside the silver, antimony, arsenic, copper, lead, iron, and zinc, 

 and sometimes gold, bismuth, nickel and cobalt ; in small quantities the 

 silver varied all the way from 15 to 200 ounces per ton, these were mixed 

 to make an average of 75 to 80 ounces per ton ; latterly the rich and 

 poor were kept separate, as it was found to be more economical to do so. 

 It was required at least that 25 per cent, of iron pyrites be contained in 

 the ore. If the amount contained in the ore was less than this, addition 

 was made either of pyrites or sulphate of iron, when the pyrites or 

 other sulphides were in excess, the roasting was resorted to to get rid of 

 it, as in the other processes. The ore was roasted in a state of fine division 

 with salt, the oxidation of the pyrites causing the evolution of chlorine 

 and hydrochloric gases, which coming in contact with silver sulphides 

 and other salts of that metal, converts them into chloride ; the ore was 

 ultimately amalgamated in revolving barrels ; a minute description of 

 this process may be found in any of the standard works on metallurgy. 

 This process was abandoned at Halsbriicke, in 1856, on account of its 

 expensiveness and its unsatisfactory results when applied to certain 

 classes of ore. Over half a century had changed the relationship exist- 

 ing between the prices of labour and fuel ; so that it was found to be 

 advantageous to give up the amalgamation process and smelt the ores with 

 others containing lead. This process has also been in use to a certain 

 extent in the United States and also in Mexico. The amalgamation 

 process employed at the Mansfield Copper Works to obtain the silver 

 contained in copper matter was similar to this, but has since been 

 abandoned for Ziervogel's process. 



In 1859 the Washoe or Pan process was invented to treat successfully 

 the ores of the great Comstock lode, situated at Virginia City in the 

 Washoe District, State of Nevada. It received the name "Washoe" 

 from its first being introduced in this district. It really owed its inven- 

 tion to the failure of both the Barrel and Patio processes, as both from 

 metallurgical and climatological conditions these processes were unsuited 

 for and proved a failure in the attempts made to apply them to the ore, 

 which contained from $30 to $150 per ton of 2,000 lbs., besides zinc 

 blende, galena, argentite, iron and copper pyrites, and sometimes ste- 

 phanite and polybasite. The gold occurring to the amount of one-third 

 of the total value of the ore, one portion of the ore only could be 

 treated by the Barrel amalgamation process, and this was that portion 



