Examination of Mines. 29 
SAMPLING. 
In sampling trenches should be cut across the vein 
or deposit (if a vein at right angles to its strike and 
dip) at not less than five (5) feet apart, and average 
samples of the ore taken therefrom; a section of the 
place sampled should be sketched in the note book, to- 
gether with a full description of each sample taken. 
From this data we determine the amount of ore in sight 
and subsequently its average value per ton. 
CLASSIFICATION OF ORES. 
High grade ores should be sampled and estimated 
separately from the lower grade ores, and in many cases 
it is necessary to divide the ores into first, second and 
third classes. 
MILL RUN SAMPLES. 
If a mill run of the ore is required, samples are 
taken, so that their total weight shall amount to one or 
more tons, and these should represent a fair average of 
all ore bodies sampled. 
LABORATORY TESTS. 
In any case it is all important that the engineer 
make laboratory or mill tests, with a view of arriving at 
the actual per cent. of concentrates contained in the ore, 
The assay value of concentrates and the approxi- 
mate amount of ore in sight which would require con- 
centrating should receive careful consideration. Free 
milling tests, amalgamation assays, cyanide and chlor- 
ination tests, etc., should also be made in order to decide 
upon the most economic process of treating the ore. 
ENGINEERS DUTIES. 
All samples of ores taken, assays of samples, labor- 
atory tests of ores, estimates of value and number of 
tons of ore in sight, investigation of title to property, 
etc., should be made in person by the engineer in charge 
