PTJRINGTON.] 
HYDKAULIT MlINTINd 
143 
In the saving of the gold, which is fine and rough, 23 Husks of quick- 
silver are distributed in the boxes. One flask of quicksilver is con- 
sumed per month. 
Six undercurrents are placed near the end of the sluice, within a 
length of from 300 to 500 feet of the end. They are transversely 
arranged, 21 by 14 feet in dimensions, and on a grade of 10 inches 
to 12 feet. They are furnished with Hungarian riffles — wooden strips 
with Hat strap iron nailed to the top. 
The first 600 feet of the nn^~U^nr-^~UY 
sluice are cleaned up month- . 
ly, and in this length 75 per 
cent of the gold is said to be 
saved. The remainder of 
the sluice is cleaned up once 
a year. The experience with 
the undercurrents was not 
satisfactory, as very little 
gold was caught in them. 
It should be especially 
noted that in the South 
Coast province the placer 
gold is of recent origin, is 
not removed more than a 
mile from its original source, 
is low in fineness (in the 
present case $16.50), and is 
bright and rough. How- 
ever finely divided, such gold 
is easy to save, and the ad- 
vantage of undercurrents 
may be questioned. In the 
interior of Alaska the case 
is different, as will be seen. 
In the Atlin district of 
ptlsh Columbia the grades 
ittainable in the tail sluices 
ire generall} 7 low, from 3 to 
) inches to the box length of 12 feet. McKee Creek forms an excep- 
tion to this rule, the grade being 8 inches in the sluices of both the 
slants now operating there. The practice of the Amalgamated McKee 
preek Mining Company on this creek is as follows: 
The sluices, of which there are two, are 600 and Too feet long. The 
•rade is 8 inches to 12 feet, and the inside dimensions of the sluice, 
xclusive of lining boards, are 29 inches wide by 3Sj inches deep, as 
lustrated in fig. 30. 
OOEZXil 
; 
Fig. 30.— Sluice box used on McKee < reek, Atlin, British 
Columbia. 
