Filter Pump

Filter Pump, an instrument in extensive use in chemical processes of filtration. Ordinary solid substances suspended in liquid are generally separated out by the chemist by filtering through specially-prepared blotting-paper. A circular disc of the paper is folded and wi-apped round the inside of a glass funnel so as to fit closely against its sides. The liquid being then poured into the funnel, passes slowly through the paper and down the tube, leaving the solid matter behind. If the process is slow on account of viscosity of the liquid or the clogging nature of the solid, the process is hastened by the filter pump, which is an arrangement for producing a partial vacuum at the lower end of the funnel and so for sucking the liquid down through the filter. It is then necessary to strengthen the lower parts of the filter paper by using a little cone of platinum foil at the apex of the funnel. In rougher operations with the filter pump the filter paper is entirely dispensed with, a small sieve of china taking its place.