A practical treatise on soluble or water glass, silicates of soda and potash, for silicifying stones, mortar, concrete, and hydraulic lime .. . s, but may also be formed by boiling fine Silexwith strong alkaline solution-. SILEX, OR SILICA, 23 It is soluble in water and acids, and when the so-lutions are concentrated it usually separates as ajelly [gelatinous silica], and when evaporated todryness, passes into the insoluble modification. Silica is a white, gritty powder, insoluble in waterand acids, infusible in the highest heat of our fur-naces, but fusible in a stream of oxygen driventhrough
A practical treatise on soluble or water glass, silicates of soda and potash, for silicifying stones, mortar, concrete, and hydraulic lime .. . s, but may also be formed by boiling fine Silexwith strong alkaline solution-. SILEX, OR SILICA, 23 It is soluble in water and acids, and when the so-lutions are concentrated it usually separates as ajelly [gelatinous silica], and when evaporated todryness, passes into the insoluble modification. Silica is a white, gritty powder, insoluble in waterand acids, infusible in the highest heat of our fur-naces, but fusible in a stream of oxygen driventhrough an alcohol flame. It fuses in this case to aclear glass, which may be drawn out into flexiblethreads. When the fused bead is dropped in water,it becomes so hard as to indent a steel pestle andmortar. It is the feeblest acid at common tempera-tures, but by a high heat can expel all volatile acids. Quartz is found in nature crystallized in a greatvariety of forms, the rhombohedral prevailing, andfor the most part hemihedral to the rhombohedron,or tetrahedral to the hexagonal prism. The annexedtwo figures give some idea of its occurrence :. The cleavage is very indistinct, sometimes effectedby plunging a heated crystal in cold water. The 24 BILEX, OR SILICA. crystals are either very short or very much elon-gated, sometimes line acicular usually implantedby one extremity of the prism, occasionally twistedor bint. The prismatic faces commonly striatedhorizontally, and thus distinguishable, in distortedcrystals from the pyramid. Crystals often groupedby juxtaposition, not proper twins, frequently inradiated masses with a surface of pyramids, orin druses having a surface of pyramids or shortcrystals. Herkimer and Ulster Counties, of theState of New York, produce quartz crystals of themost complicated forms, which occur from the sizeof a pins head to that of a foot. Quarts is alsofound massive, from the coarse or fine granular toflint-like or crypto-crystalline; sometimes mamillary-ta
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Keywords: ., bookcentury1800, bookdecade1870, bookidpracticaltre, bookyear1870
