202 
GRAVEL AND PLACER MINING IN ALASKA. 
[bull. 263, 
the depth of one-half inch. Some operators claim that a recurring 
quick jar imparted to the fine gold tables by means of an eccentric or 
other device aids the saving of the gold. The efficiency of this prin- 
ciple is questionable. 
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— 2 feet 
Fig. 46.— Riffle to hold divided sheet of quicksilver. 
H 
On the Snowfiake claim, a bench claim, worked by drifting, situated 
between Anvil and Dexter creeks, much of the gold sluiced from the 
winter dump was porous, occurring in lumps one thirty-second to one- 
fourth inch in diameter, resembling dentist's gold. A peculiar riffle 
shown in fig. 47 was devised, consisting of sawn blocks nailed to riffle 
strips. 
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Fig. 47.— Special block riffle for saving porous gold. 
This riffle used in 14-inch boxes, on 8-inch grade, with 50 miner's 
inches of water, was said to be the only one of many tried which would 
catch this gold. 
