2818. Fuchs' Soluble Soda Glass

2818.     Fuchs' Soluble Soda Glass. This is prepared in the same way as the potash glass (see No. 2817 (Fuchs' Soluble Potash Glass)), with the exception that a smaller proportion of soda is required. A mixture of 45 parts by weight of quartz, 23 parts dry carbonate of soda, and 3 parts charcoal, may bo employed. The mixture fuses somewhat easier than potash glass.

2819. Buckner's Soluble Soda Glass

2819.    Buckner's Soluble Soda Glass. Take 100 parts quartz, 60 parts dry sulphate of soda, and 15 to 20 parts charcoal. This is said to be cheaper than that made with carbonate of soda, and is prepared in the same manner. By the addition of some copper scales to the mixture the sulphur will bo separated. Another method is proposed by dissolving the fine silex in caustic soda lye. Kuhlman employs the powdered flint, which is dissolved in an iron caldron under a pressure of 7 to 8 atmospheres of steam. Liebig has recommended infusorial earth in place of sand, on account of its being readily soluble in caustic lye; and ho proposes to use 120 parts of the earth to 75 parts of caustic soda, from which 240 parts of silica jelly may be obtained. His mode is to calcine the earth so as to become white, and passing it through a sieve. The lye he prepares from 75 ounces of calcined soda, dissolved in 5 times the quantity of boiling water, and then treated by 56 ounces of dry slacked lime; this lye is concentrated by boiling down to 48° Baum'e; in this boiling lye 120 ounces of the prepared infusorial earth are added by degrees, which are readily dissolved, leaving scarcely any sediment. It has then to undergo several operations for making it suitable for use, such as treating again with lime-water, boiling it and separating any precipitate, which by continued boiling forms into balls, and which can then be removed from the liquid. This clear liquid is then evaporated to the consistency of syrup; it forms a jelly slightly colored, feels dry and not sticky, and is readily soluble in boiling water. The difference between potash and soda soluble glass is not material; the first may be preferred in whitewashing with plaster of Paris, while the soda glass is more fluidly divisible.

2820. To Distinguish Potash and Soda Soluble Glass

2820.    To Distinguish Potash and Soda Soluble Glass. By adding 1/4 volume of recti tied alcohol to a concentrated solution of soluble potash glass, a gelatinous precipitate is formed, which, in a few days, is deposited at the bottom of the vessel in a solid mass. The addition of alcohol to soluble soda glass converts it into a gelatinous mass, but affords no precipitate.

2821. To Make Wood Incombustible

2821.    To Make Wood Incombustible. The application of soluble glass to wood renders it almost incombustible.

2822. Double Soluble Glass

2822.    Double Soluble Glass. A mixture of 3 parts by measure of concentrated potash soluble glass, and 2 parts concentrated soda glass, produce a double water-glass which will answer all practical purposes.

The following preparation is also recommended by Fuchs, as being much easier to fuse. Take 100 parts quartz, 28 parts purified potash, 22 parts neutral dry carbonate of soda, ' and 6 parts powdered charcoal.

2823. Soluble Glass for Stereo-Chromic Painting

2823. Soluble Glass for Stereo-Chromic Painting. Soluble glass for the use of stereo-chromic painting is obtained by fusing 3 parts of pure carbonate of soda and 2 parts of powdered quartz, from which a concentrated solution is prepared, 1 part of which is then added to 4 parts of a concentrated and fully saturated solution of potash-glass solution, by which there is a more condensed amount of ; silica with the alkalies; this solution has "' been found to work well for paint. Siemens' patent for the manufacture of soluble glass consists in the production of a liquid quartz by digesting the sand or quartz in a steam-boiler tightly closed and at a temperature corresponding to 4 or 5 atmospheres, with the common caustic alkalies, which are in this way capacitated to dissolve from 3 to 4 times the weight of silica to a thin liquid. Experience has taught that the soluble glass made in the old way, with an excess of alkali, cannot stand the influence of the atmosphere when used as a paint. The soda washes out, and leaves the silex in a pulverized condition, so that it soon disappears. When, however, a closed boiler is used, according to Kuhlman's or Siemens' method, and a pressure of 7 or 8 atmospheres, which corresponds with a temperature of some 120° above the boiling point of water, the solvent qualities of the latter are increased to such an extent as to enable it to dissolve a glass containing 1/3 to 1/2 the amount of potash or soda.