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Updated: May 24, 2025
It is quite common to see the sticks so used attached to the clothing or bundles in travelling; they wet the blunt end of the upright stick with the tongue, and dip it in the sand to make some particles of silica adhere before inserting it in the horizontal piece. The wood of a certain wild fig-tree is esteemed as yielding fire readily.
Rosales's theory account at all for auriferous lodes; which below water level are composed of a solid mass of sulphide of iron with traces of other sulphides, gold, calcspar, and a comparatively small percentage of silica.
Ignition of substances not requiring too high a temperature may be made in porcelain or silica crucibles. Iron, nickel or silver crucibles are used in special cases. In general, platinum crucibles should be used whenever such use is practicable, and this is the custom in private, research or commercial laboratories.
The geyser-waters hold large quantities of silica and sulphur in solution, owing to their high temperature under great pressure, and these minerals are precipitated upon the cooling of the waters in the air, and form circular basins, often gorgeously tinted with red and yellow colours. J. W. Powell, Exploration of the Cañons of the Colorado, pp. 114, 196.
Pure silica in the state of hard, rock crystal is a better conductor than bismuth or lead; but if the rock crystal be pulverized, the diffusion of heat through its powder is very slow and feeble. Heat is conducted swiftly and copiously through transparent rock salt, but pulverization converts the solid mass into a good non-conductor.
The process of bolting removes all the woody fibre; the lime needed for the bones; the silica for hair, nails, and teeth; the iron for the blood; and most of the nitrogen and phosphorus needed for muscles, brain, and nerves.
It kept continually filled an oval basin about 250 feet in circumference the margins of which were fringed all round with beautiful pure white stalactites, formed by deposits of silica, with which the hot water was strongly impregnated. At various stages below the principal spring were several others, that contributed to feed the lake at the bottom, in the centre of which was a small island.
It is much more rational to suppose that the increased hardness imparted to the slates and schists at or near their contact with the lode is due to an infiltration of silica from the silicated solution which at one time filled the fissure.
Turner found the ignited Indian tabasheer to consist almost entirely of pure silica with a minute quantity of lime and vegetable matter. He failed to find any trace of alkalies in it. It gave the following result: Silica. = 96.94 Potash and lime. = 0.13 Water. = 2.93 Organic matter. = trace
But the limestone contains very little silica, and is apparently of normal composition quite up to the vein. From the trap? This is compact, sonorous basalt, apparently unchanged; and that could not have supplied the silica without complete decomposition.
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