|
52 PRECIOUS STONES
|
||
|
|
||
|
CHAPTER IX.
PHYSICAL PROPERTIES.
G—Heat.
Another method of isolating certain stones is by the action of heat-rays. Remembering our lessons in physics we recall that just as light-rays may be refracted, absorbed, or reflected, according to the media through which they are caused to pass, so do heat-rays possess similar properties. Therefore, if heat-rays are projected through precious stones, or brought to bear on them in some other manner than by simple projection, they will be refracted, absorbed, or reflected by the stones in the same manner as if they were light-rays, and just as certain stones allow light to pass through their substance, whilst others are opaque, so do some stones offer no resistance to the passage of heat-rays, but allow them free movement through
the substance, whilst, in other cases, no passage of heat is possible,
the stones being as opaque to heat as to light. Indeed, the properties
of light and heat are in many ways identical, though the test by heat
must in all cases give place to that by light, which latter is by far of the greater importance in the judging and isolation of precious stones. It will readily be understood that in the spectrum the outer or extreme light-rays at each side .are more or less bent or diverted, but those nearest the
|
||
|
|
||