Willstatter ’filtration nail

An apparatus for the filtration of small to moderate quantities of crystals incorporates the so-called Willstatter filtration nail. The latter consists of a thin glass rod flattened at one end. It is readily constructed by heating the end of a short glass rod in the blowpipe flame and pressing vertically upon an asbestos board. The nail is fitted into small glass funnel it is covered by a circle of a filter paper cut with the aid of a cork borer of appropriate size. A filtration nail r r and funnel, capable of handling up to 1 g. of solid is depicted... 

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