Fig. 1.

a Scanning electron microscopic photograph of a nickel-mesh-filter. Magnification of a single pore in nickel-mesh shows the smooth transition into the pore interior (inset). b Schematic illustration of gravity-based, nickel-mesh-filtration system. Height of the meniscus within the vertical tube (h) was obtained by continuous reduction of filtration pressure (P), specific gravity (ρ), and acceleration of gravity (g). Flow rate (Q) was calculated automatically by the first time derivatives of h (dh/dt) and internal cross-sectional area of the vertical tube. D internal diameter of vertical tube. c Photograph of computer screen showing P–Q (upper right) and h–t (lower) relationships