MAKING MARBLE OF SOFT STONE.

North Otago Times, 3 September 1910, Page 1 (Supplement)

MAKING MARBLE OF SOFT STONE.

! By new methods, soft sandstone or limestone, or even mortar or coni crete, is made hard and imperme- ' able to a,depth of half an inch or 1 so, and after treatment can be! 1 polished and cut. This makes it practicable to use soft and easily < worked stones where the hard ma-. ! terial is needed, as in tanks, pave- ■ ' ments, etc. In one process, the sur- j 1 face of the stone is first thoroughly ■ cleansed, cavities are filled with ( cement mortar tempered with water j 1 glass solution, the whole is then saturated with a solution of potash !■ , or soda water-glass, and is finally impregnated with molten chloride of I ! calcium. The reaction of the chloride of calcium on the water-glass fills the pores wjtu hard, insoluble j silicate of lime. Another process • i consists in first saturating with sulphate of ammonia solution, and then . with a solution of potash water : j glass, wiping off the solution not absorbed in one minute. HOW TO FASTEN RUBBER TO METAL., Rubber matting used in motor' ' cars can bo secured to a metal sur-1 face, it has been found, by using a' .1 cement made of flake shellac dis- : I solved in alcohol to form a thick ' 'syrup. Several thin coats carefully I 1 applied should be given to each sur-1 facet, each subsequent coat to be ap- ' plied before the last is dry. Press the rubber upon the coated metal, ! taking care to have all the surface j j in contact, and by the use of a hoard ] .and rather heavy weights, keep the surfaces pressed together for about 1 24 hours.