. Inorganic chemistry . in a platinum crucible till it fuses into a glassy mass. Thecontents of the crucible are then boiled with water, to whichhydrochloric acid in excess is afterwards added, and the wholeevaporated to dryness. 463. During the fusion, the silica enters into combinationwith the potass and soda (liberating the carbonic acid), andabandoning any oxide with which it was previously in hydrochloric acid sets thesilicic acid free, combining withthe alkalies to its exclusion, andat the same time uniting itselfto whatever oxides were origin-ally present in the mineral. These
. Inorganic chemistry . in a platinum crucible till it fuses into a glassy mass. Thecontents of the crucible are then boiled with water, to whichhydrochloric acid in excess is afterwards added, and the wholeevaporated to dryness. 463. During the fusion, the silica enters into combinationwith the potass and soda (liberating the carbonic acid), andabandoning any oxide with which it was previously in hydrochloric acid sets thesilicic acid free, combining withthe alkalies to its exclusion, andat the same time uniting itselfto whatever oxides were origin-ally present in the mineral. Theseparated silica is to some ex-tent dissolved by the dilutedacid, but after the evaporationof the liquid to perfect dryness,it loses its solubility, and whenacidulated water is poured uponthe desiccated mass, it dissolveseverything but the silica, whichit leaves untouched. 464. Another method of pre-paring silica in a fine state of division is to take a mixture ofequal parts of powdered fluorspar and glass, and introduce. Fig. 49. 154 Chemistry. these into a flask, where they are drenched with sulphuric bent tube is introduced into the flask, the other end of whichdips into a receiving vessel, containing enough mercury to coverthe end of the tube, and thereafter filled up with water (fig. 49).The gas evolved is decomposed when it enters the water, andsilica in a gelatinous form is separated. When the gelatinoussilica is washed with water and dried, it is obtained as a veryfine and light powder, which can be blown about with a breathof wind. 465. Properties.—Silica is a snow-white,.gritty powder, which,after being strongly heated, is quite insoluble in water, acids,and indeed most liquids. It is infusible by the most powerfulwind-furnace, but melts when exposed to the intense flame ofthe oxyhydrogen blowpipe. Its sp. gr. is 2-642 when crystallised,and 2-2 to 2-3 when in the amorphous or non-crystalline spite of its insolubility in water in its ordinary gritty sta
Size: 1379px × 1812px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauth, bookcentury1800, bookdecade1860, bookidcu31924031265709
