If one button has twice the diameter of another it
is eight times as heavy and so on. Scales specially constructed for
measuring silver and gold buttons may be purchased; but it is much
better to make the measurement with the help of a microscope provided
with an eyepiece micrometer.
If the length of the long diameter of a silver button be taken the
following table will give the corresponding weight in milligrams:--
------------+-----------++------------+---------
Diameter. | Weight. || Diameter. | Weight.
------------------------------------------------
0.04 inch | 3.6 || 0.015 inch | 0.19
0.035 " | 2.4 || 0.014 " | 0.15
0.03 " | 1.5 || 0.013 " | 0.12
0.025 " | 0.9 || 0.012 " | 0.097
0.02 " | 0.45 || 0.011 " | 0.075
0.019 " | 0.4 || 0.010 " | 0.056
0.018 " | 0.33 || 0.008 " | 0.028
0.017 " | 0.27 || 0.006 " | 0.012
0.016 " | 0.23 || 0.004 " | 0.004
------------+-----------++------------+---------
The weight of a corresponding button of gold is got by multiplying by
2.25. These figures are based on those given by Plattner, and apply only
to buttons of such shape as those left after cupellation. A sphere of
silver 0.01 inch in diameter would weigh 0.
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