Handy Mining Camp How-To

HORSE-POWER OF AN ENGINE.
Multiply the area of the cylinder in square inches by the average
effective pressure in pounds to the square inch, deducting three pounds
per square inch for friction. Multiply this remainder by the speed of
the piston in feet per minute, and divide by 33,000. The quotient will be
the true horse-power.

AMOUNT OF GOLD IN QUARTZ
Rule for ascertaining the amount of gold in a lump
of auriferous quartz, according to Phillips:

The Specific gravity of gold is 19.000.
The specific gravity of quartz is 2.600.

These numbers are given here merely for conven-
ience in explaining the rule; they do not accurately
represent the specific gravities of all quartz and
quartz gold. (The quartz gold of California has
not, on an average, a specific gravity of more than
18.600.)

1. Ascertain the specific gravity of the lump.
Suppose it to be 8.067.

2. Deduct the specific gravity of the lump from
the specific gravity of the gold; the difference is
the ratio of the quartz by volume: 19.000-8.067
= 10.933.

3. Deduct the specific gravity of the quartz from
the Specific gravity of the lump; the difference is
the ratio of the gold by volume: 8.067-2.600 =
5.467.

4 Add these ratios together and proceed by the
rule of proportion. The product is the percentage
of gold by bulk: 10.933 + 5.467 = 16.400. Then,
as 16.400 is to 5.467, so is 100 to 33.35.

5. Multiply the percentage of gold in bulk by its
Specific gravity. The product is the ratio of the
gold in the lump by weights 33.35 x 19.00 =
613.65.

6. Multiply the percentage of quartz by bulk
(which must be 66.65, since that of gold is 33.35)
by its specific gravity. 'l'he product is the ratio
of the quartz in the lump by weight: 66.65 x 2.60
= 173.29.

7. To find the percentage, add these two ratios
together and proceed by the rule of proportion:
633.65 + 173.29 = 806.94. Then as 806.94 is to
633.65, so is 100 to 78.53. Hence, a lump of aurif-
erous quartz having a specific gravity of 8.067, con-
tains 78.53 per cent. of gold by weight.

(The Mines, Miners, and Mining Interests of the United
States in 1882, by Wm. Ralston Baleh, Phila., p.761.)

MINER'S INCH.
A miner's inch of water varies in different States, and is, therefore, not
a fixed quantity. In some States it means the quantity of water that will
flow through an orifice one-inch square on the bottom or side of a box
under a pressure of four inches. Under these conditions a miner's inch
will discharge 2259 cubic feet, or 17,648 gallons every twenty-four
hours, which is at the rate of 12 gallons a minute. Fifty of these miner's
inches are equal to a cubic foot of water discharged every second. One
cubic foot of water a second would be sufficient to supply the wants of
seven thousand city dwellers.

In calculating the amount of water required by a stamp mill it is usual to
allow 72 gallons for every stamp, 120 gallons for every pan, 75 gallons
for every settler, 120 gallons for every Fruevanner, 30 gallons for a
concentrator, 350 gallons for a jig, and 71 gallons for every horse-power
of a boiler each hour. If the water after passing through the mill is impounded
and used over again, the loss will be about 25 per cent.

Common Mining Weights
Average Weight of one ton of earth sand gravel etc..

cubic foot cubic yards

shingles......23.........0.85
pit-sand......22.........0.81
earth.........21.........0.77
river-sand....19.........0.70
coarse-gravel.19.........0.70
clay..........18.........0.66
marl..........18.........0.66
chalk.........14.........0.52

Weights of ores and rocks pounds per cubic foot:

cinnabar........549
galena..........461
silver glance...455
brittle silver..386
ruby silver.....362
horn silver.....345
iron pyrites....312
antimony glance.287
gray copper.....280
copper pyrites..262
zinc blende.....249
limestone.......174
Quartz..........162
clay............162

CALCULATING WEIGHT OF ORE.
Measure the cubic contents of the mass; multiply this by the weight of
one cubic foot of the mineral. For small masses, where no scales are at
hand, fill a bucket with water, and stand it in an empty barrel. Fill the
bucket brimful; introduce the rock, or ore, and measure the water it
displaces. Find the number of cubic inches in the overflow by
reference to the following table:

1 gallon equals 231 cubic inches.
1 quart equals 57.75 cubic inches
1 pint equals 28.87 cubic inches.
1 gill equals 7.21 cubic inches.

Multiply the total so found by the specific gravity of the ore, and the
result will be the answer sought. Supposing the bottom of the bin to be
wedge-shaped, measure half the height from the bottom to the top and
multiply the number of feet by the width and length, both in feet. This
will give number of cubic feet in the bin. Multiply the number of
cubic feet by the weight of one cubic foot of the ore, and the result will
show the number of pounds of ore the bin will hold. Divide by 2,000 to
reduce to tons.

HORSE-POWER OF PELTON WHEEL.
The Pelton wheel is in high favor with California miners.
When the head of water is known in feet, multiply by
0.0024147 and the product is the horse-power that one
miner's inch of water will give.

TO FIND THE DEPTH OF A SHAFT

Rule:--Square the number of seconds a stone takes to reach the
bottom and multiply by 16.

Thus, if a stone takes 5 seconds to fall to the bottom of a shaft--

5 squared = 25; and 25 X 16 = 400 feet, the required depth of shaft.

STAMP-shaft depth,MILL HORSE POWER
To find the horse-power required to drive a battery, multiply the
weight of one stamp by the number of stamps in the battery; the height
of lift in feet by the number of lifts per minute; add one-third of
the product for friction, and the result will be the number of feet-
lbs. per minute; divide this by 33,000 which is the number of feet-
lbs. per minute equal to 1 h.-p. and the result will be the h.-p.
required. Thus if a stamp weighs 800 lb. and you have five in the box,
and each stamp has a lift of 9 in. = 0.75 ft. and strikes 80 blows per
minute, then 800 x 5 x 0.75 x 80 = 240,000; one-third of 240,000 =
80,000 which added to 240,000 = 320,000; and 320,000 divided by 33,000
= 9.7 h.-p. or 1.9 h.-p. each stamp.