36 GOLD MINING IN NOKTH CABOLINA.
mines of the Southern States have been overrun. Although some of these, notably the Huntington mill, are still in use at a few places, it has been quite clearly demonstrated that such grinding apparatus produces float gold and flours the quicksilver, besides which the mechanism is subjected to great strain and wear, against all of which defects the stamp battery, with plate amalgamation, has proven itself vastly superior, and through all of its vicissitudes it has held the field as the most economical and rational apparatus for milling and amalgamating gold ores.
TREATMENT OF STJLPHTJRET ORES.
As soon as the water-level was reached in the mines, and the freemilling brown ores were practically exhausted, attempts were made to treat the undecomposed sulphurets.
MECHANICAL METHODS.
Probably the earliest method employed for the concentration of these sulphurets was that used at the Vaucluse mine in 1847 (described on page 31), which consisted in passing the material over strakes or inclined planes. This was probably followed by buddies, primitive bumping-tables and more especially by blankets. Log rockers were also used at an early date for this purpose. At the present day the Frue, Embrey and Triumph concentrators are in general use. Of these, the Embrey machine is considered by some to give better results, especially where skilled labor cannot be obtained, and where the sulphurets are not sized. Still, each one of the three finds its strong advocates, and the difference in perfection of concentration obtained by them is probably not material. In some cases as, for instance, in the Gold Hill district the finely-divided condition of the gold has led to the re-employment of blankets.
At the Reimer mine, K"orth Carolina, a plant was in operation in 1SS3 in which the ore was comminuted in a series of crushers and 26inch rolls; the pulp was sized into six grades, from 10- to 60-mesh, and each grade treated separately by a Bradford jig. This process is said to have given good results, but the plant was destroyed by fire soon after its erection and never rebuilt. The same system of jigging was at one time in use at the McGinn mine in Xorth Carolina.
The earliest treatment of the concentrated sulphurets was by regrinding them (in the raw, unroasted state) in Mexican arrastras and Chilean mills, with subsequent amalgamation, as described above in the practice of working the ores at the Vaucluse mine, Virginia, in 1847.
In 1852-53, a Dr. Holland, of Massachusetts, introduced a roasting process at some mines near Charlotte. X. C, in which the pyritic eon-
