GB202143A - Improvements in or relating to filters - Google Patents

Abstract

202,143. Bechold, H. July 17, 1922. Sterilizing liquids.-In order to secure a sterile filtrate, materials such as diatomaceous earth, cellulose, clay, sand, gravel, and coke, used for filtering water, fruit juices, serum, toxins, and other liquids, are impregnated with metals having a lower solution tension than hydrogen or compounds of such metals which are not readily soluble. In the case of metals, two are used together and the metals are of higher solution tension than platinum, or one is of higher solution tension than platinum and the other of lower solution tension than silver. Suitable substances include copper, copper oxide, copper ferrocyanide, copper carbonate, silver, silver oxide, silver sulpho-cyanate, silver chloride, silver chromate, mercury, mercuric oxide, mercurous chloride, bismuth, bismuth trioxide and pentoxide, arsenic, antimony, and antimony oxide. Amalgams or alloys may be used. The impregnating-materials mav be deposited in the filtering-mass by chemical action therein, or introduced in a gaseous state. Auxiliary substances which will serve to maintain a uniform distribution of the active material may be used. In one example, filtering-material is impregnated with silver chloride by first introducing gaseous ammonium chloride and then a solution of silver nitrate. In a second example, the filtering-material is treated successively with solutions of tannin or albumen, mercuric chloride, and caustic soda, the material being thus impregnated with mercury or mercuric oxide. In a third example, filtering-material is impregnated with copper by treating it with a solution of copper sulphate mixed with cane sugar or dextrin and then drying and heating.