The technique of preparing active cell suspensions of Cl. acetobutylicum (Weizmann) capable of giving normal fermentation products from glucose has been described [Davies & Stephenson, 1941]. It was stated that these suspensions rapidly lost their activity. In the present paper further experiments on the decay of activity are described and also various experiments on reactions performed by susp...

The gravity sedimentation of three narrow-sized fractions of suspensions of magnetite particles exposed to magnetic fields ranging from 0 to 180 x 10 -4 T was studied experimentally. At volumetric solids concentrations in excess of 15%, the magnetized suspensions of magnetite with size fractions ranging from -75 to +38 μm settled more slowly than the non-magnetized suspensions. However, owing t...

A photoelectric turbidimeter is described for use in measuring cell concentrations in thick suspensions. Its sample cuvette provides a path length continuously adjustable between 0.01 and 20.00 mm. By reducing the path length, it is possible to measure the optical density in thick cell suspensions without dilution. Moreover, the method described is rapid and simple, and only small amounts (less...