A Device for Filtering Toxins, etc., by the Use of Water Pressure.

The use of gas or air pressure to drive toxins, or other bacterial fluids, which it is desired to filter, and at the same time to sterilize through bougies of porcelain etc., has been common for a long time. The ordinary aspiration filter is, of course, really a pressure filter, the limit of pressure being rather less than one atmosphere, and depending on the degree of exhaustion obtainable. But direct air or gas pressure?secured say by compression?has always presented, besides the mechanical difficulties, chemical or physical difficulties, dependent on the pressure-modifications of the action of the gases used upon the liquids to be filtered. It occurred to the writer that the interposition of a thin sheet of rubber between the surface of the liquid to be filtered and the liquid (air, gas, or water) which was used as the vehicle to transmit the pressure would at once remove almost all the objections which could be brought against pressure filtration. Because of its relative density and inelasticity, water presents so many mechanical advantages over air, that attention was concentrated wholly upon the use of water