Recent Changes in Gold Mining 
111 
/907] 
to the ore. Unless the ore body is large, no mill should be in- 
stalled until the changed ore below the water level has been 
tested. 
In North Carolina there seem to be only a few miners who 
deceive themselves by assaying the rich streak and assuming 
that the entire streak will be equally as good. The general 
principles of sampling the entire body seem to be well under- 
stood, although it is not always done as accurately as it 
should be. 
Even when good ore occurs in paying quantities the miner 
frequently builds a mill that is too large; For there is only a 
little extra expense in increasing the size of the mill after it 
has been running awhile instead of building a large mill all at 
once. So there is little excuse for assuming the greater risk 
of a large mill. There is less loss of gold in adjusting a 
small mill. 
One agreeable exception to the practice of building a mill 
before the mine is sufficienty developed is seen in the work of 
the Whitney Company, who have carefully tested and 
explored a number of mines. Many of the options were given 
up of course. At the old McMakin Mine at Gold Hill, as 
explorations proved the value of the mine, the contemplated 
scale of working was gradually increased. When the small 
shafts of the upper levels were deepened, the lower parts 
were made large enough for balanced hoisting and the small 
part will be enlarged later. In the meantime most careful 
sampling and assaying was done and when enough ore had 
been blockedout, careful mill tests were made chiefly upon the 
material obtained from drifts. In this way a total of 4,950 
tons of ore was run through the little mill on the ground; 
careful records of everything gave an average recovery of 
$4.52 of gold on the plates and only $0.34 per ton as a concen- 
trate worth but $5.03 per ton and $0.83 per ton in the tail- 
ings. These tests made clear that the most economical 
method is simple amalgamation, giving a saving of about 80 
per cent of the gold, with no attempt to concentrate and treat 
the concentrates. 
