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ELECTRICAL PROPERTIES:
In a general manner, all bodies acquire electricity by friction; only, one kind keep for a longer or shorter time the electricity confined as it were in their pores, while the other kind lose it instantly. The first are isolating bodies, the others are conducting bodies.
Precious stones belong to the first of these categories; but they exhibit great difference in the time during which they remain electrified; and this characteristic affords, in experienced hands, a very useful test for distinguishing one from another.
There are certain precious stones which possess the curious quality of becoming electric when they are subjected to heat. The tourmaline is especially susceptible to this thermotic electricity.
When precious stones are rubbed with the same material, usually a bit of cloth, some of them acquire positive electricity and the others negative electricity. Tourmaline, and other substances electrified by heat, usually exhibit positive electricity at one extremity and negative at the other. |
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Precious Stones Guide Vol 2
>> Physical Characteristics of Precious Stones: Electrical Properties
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