paper is substituted instead of cloth or flannel; through this substance, no solid body,however finely it be powdered, can penetrate, and fluids percolate through it with thegreatest readiness. As paper breaks easily when wet, various methods of supporting it areused according to circumstances. When a large quantity of fluid is to be filtrated, thepaper is supported by the frame of wood, Pl. II. Fig. 3. ABCD, having a piece of coarsecloth stretched over it, by means of ironhooks. This cloth must be well cleaned eachtime it is used, or even new cloth must be employed, if there is reason to suspect its beingimpregnated with any thing which can injure the subsequent operations. In ordinaryoperations, where moderate quantities of fluid are to be filtrated, different kinds of glassfunnels are used for supporting the paper, as represented Pl. II. Fig. 5. 6. and 7. Whenseveral filtrations must be carried on at once, the board or shelf AB, Fig. 9. supportedupon stands C and D, and pierced with round holes, is very convenient for containing thefunnels.