The San Francisco call., 1895-11-14

month and rs per cent the next month.
He thought if all conditions were favor
able SO per cent might be secured, al
though the very next 10000 tons might
make only rs. He thought 70 per cent
would be fair average of battery samples.
Continuing to speak of battery samples he
thought 81 per cent an extraordinary low
rate, and, if he were the owner, he would
not be satisfied.
Under proper condition Mr.. Mackay
said that the percentase returned from d
body of ore of about $4,000 tons, the
assay value being $50 or $40 ton, ought to
be 70 or IS per cent on car samples. The
difference between car and pulp samples
range all the way from 81 to $40.
Mr.. Mackay was questioned closely as
to what rock must assay to be worth
working and the differences between car,
battery and wagon samples. He said the
character of rock or car sample that would
pay to work depended on various condl-
tions. He said of late years they always
calculate the returns of battery assays.
When they used to ship IN early days it
was 65 per cent from wagon samples. In the
example of sc, 900 tons of rock averaging $39
per ton there might be as great differ
ence between the pulp and the car as $40,
or So or S.. There is always some differ
rock ought to be 20 per cent by battery
sample.
There was very lengthy examination at
this point of the correctness of the various
methods of sampling, Mr.. Mackay bellev-
ing that battery sampling was more nearl ly
accurate.
There is difference of from 81 to $40 be-
tween pulp and box, or railroad samples,
pulp being always less than the car. He
believed that of the $4,000 tons, the amour
it ran in the Norcross, if sampled in cars,
the average of the car samples would
closely approximate the value of the ore at
the mine, but not at the mill. The correct
value OF the ore is obtained from the bat
terry samples. He said he had an interest
in the working of the tailings of the Eu-
reka mill. The Comstoek Mill and Mining
Company let the contract to work the
shines to Mr.. Peck at 81 ID ton. He said
he had not helped Mr.. Peck with money
and did not know how much Peck was
making out of the contract.
On cross-examination he said that as a
general thing there should be return
OF from 20 to IS per cent of pulp
assays. He wouldn't guarantee 70
per cent of battery assays, although
it might return 80 per cent. During
the last fifteen years he hasn't known
of any mill-owner working ores from
the Comstock lode to agree to work
ore ores according to the car-sample assays
The percentage of the yield varies with
the value of the ore. He said that in the
ore worked in the Hale & Norcross from
1868 to 1874 there was considerable masses
of low-grade ore, and this is true of ali
veins on the Comstock. The rich and
poor ore is taken together to the mill. 1t
wouldn't pay to separate the high and
low grade ores. Barren streaks are some
times broken down and sent to the mills
In the Hale & Norcross in early days they
were troubled with clay streaks of black
oxide OF manganese. Ii 65 per cent was
the standard gauge the millman would
have to pay the difference where the re-
suits fell below that gauge. and if they
ran above, the mine man got the dif-
ference.
The cause will proceed to-day.