HISTORICAL >'OTES: JIINIXG, METALLL'KGICAL AND STATISTICAL. 33 EARLY JIILL1XG APPLIANCES.
Tor a long time the output was confined to the free-milling brown ores near the surface, and the ore was raised by horse-whim and handwindlass, or even by baskets carried upon the backs of the miners. At first the gold from the ores of the decomposed outcrops of the veins was extracted by washing in rockers. The following quotation from Prof. Elisha Mitchell's Report on the Geology of North Carolina (1S27), is pertinent here:
" The quartz is raised from the mine, broken to pieces, and those parts which are known to contain gold selected for washing. This part of the process is conducted in the same way as in Montgomery (county), except that the agitation is continued for a longer time, and that a small quantity of quicksilver is put into the rockers to collect the gold, by forming an amalgam with it."
The most primitive method of milling the quartz was undoubtedly by crushing in hand-mortars and subsequent panning. This is still earned on by the native tributors in certain districts. It was followed by the introduction of the drag mill (arrastra), the Chilean mill (Plate I, p. 30) and eventually the stamp-mill. The two former were evidently drawn from South American and Mexican practice, and were probably the first mechanical pulverizing machinery used.
As an illustration of some of the earlier milling methods, the following is taken from a report of the Supervising Committee of the United States Mining Company in 1835, on their mine near the Rappahannock river, Virginia:
" The plant consists of a crushing (rolls) and a vertical mill (stamping-mill) in a building 26 x 30 feet. Both mills are located on the ground floor and are propelled by a water-wheel 11 feet in diameter, with a 11-foot face. The crushing-mill has 3 sets of cylinders 2 feet in length and 15 inches in diameter, the first or upper set fluted, the other smooth. The ore is thrown into a hopper on the upper floor, from which it is conducted over an inclined shaking-table to the fluted cylinders, by which it is crushed to a size from 14 to 1 inch in diameter. The crushed material is equally divided and goes to the two sets of smooth cylinders. By them it is further greatly reduced, ranging from impalpable powder to grains as large as coarse hominy. From these cylinders it falls into a sifter having the fineness and motion of the common meal-sifter, from whence the material which passes through is conducted to 12 amalgamators, constructed upon the principle of the Tyrolese bowls, making from 90 to 100 revolutions per minute. They perform the office of washing and amalgamating. The sand discarded by them, after being washed, is conducted through troughs to the vertical mill, where, being reduced to an impalpable powder, it passes in the shape of turbid or muddy water to another set of amalgamators similar to those above mentioned, and thence to the river. The portion of the ore reduced by the cylinders which passes over the sifters is conducted to the vertical mill, and is treated in the same manner."
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