; but in this
case it would be well, in order to avoid a somewhat shallow criticism,
to replace the term "moisture" by the longer but equivalent phrase
"water lost at 100° C."
~Calculation and Statement of Results.~--By far the most generally
convenient method of stating the results of an assay is that of the
percentage or parts in a hundred, and to avoid a needlessly troublesome
calculation it is well to take such a quantity of ore for each assay as
by a simple multiplication will yield the percentage. In these
calculations decimals are freely employed, and students should make
themselves familiar with the methods of using them.
Other methods of statement are in use, and have advantages in certain
special cases. With bullion the parts in a thousand are given, and in
those cases in which the percentage is very small, as in water analysis,
it is convenient to report on parts in 100,000, or even on parts per
1,000,000. These are easily got from the corresponding percentages by
shifting the decimal point one, three, or four places to the right. Thus
92.5 per cent. is 925 per thousand; and 0.0036 per cent. is 3.6 per
100,000, or 36 per million.
With ores of tin, silver, and gold, the result is stated as so many
cwts., lbs., or ozs., in the ton. With dressed tin ores as they are
sent to the smelter, the produce is given in cwts.
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