FUCHS'S SOLUBLE GLASS is a peculiar silicate,which is prepared by melting together 8 parts of carbonate of soda, or 10 parts of carbonate of potash, with 15 of pure quartz sand, and 1 part of charcoal, which is added to facilitate the decomposition of the alka line carbonate. A black glass is thus-obtained, which is not soluble in cold water, but dissolves in about six times its weight of boiling water. Fuchs commenced his experi ments on this subject in 1825, and has continued and varied them ever since. The above is, however, we believe, the most approved formula. The practical uses of the soluble glass to which he especially directed his attention were two—viz. (1), as a var nish, which, applied in the fluid form to stone surfaces, would harden into a glass, and prevent the ordinary effects of atmospheric influences; and (2) as a means of fixing fresco colors by the process known as stereochromy, At the request of thd late prince consort, Dr. Fuchs gave a summary of all that lie had done in this department in a paper which he the society of arts iu 1859. See FRESCO.
It may be mentioned that prof. Kuhlmann of Lille has been long working at the same subject; and in 1837, published his method of producing a stone-protecting sili cate; and that our own countryman, Mr. Ransome of Ipswich, has not only employed concentrated solutions of silicate of potash, or of soda, as a cement for. consolidating silicious sand into a very hard, durable, artificial sandstone, capable, before it is fired, of being molded into any desired form, but has likewise produced a vitreous varnish, consisting of silicate of potash, after which lie applies a coating of a solution of chlo ride of calcium: a silicate of lime is thus formed, which is stated to be very successful in protecting the surface of stone from external influence. Wood that has begn painted with these varieties of soluble glass is rendered nearly if not quite fire-proof.