Zur Methodik der Bestimmung kleinster Mengen Borsäure

Boron Determination in Soils and Plants

“…The shape factor of small particles should approximate that for a sphere as their particle size decreases, particularly since the methods used for the measurement of their diameters frequently does not distinguish any dominant irregularities. However this may be, there are data to warrant the assumption that a representative sample of an aggregate has a fairly constant shape factor (1,8). This paper furnishes experimental evidence of the variation in shape factor for crushed quartz particles between the range of 10-and 40-mesh Bureau of Standards calibrated screens.…”

“…The particles were carefully sieved and average diameters of upwards to 1000 particles in each sample determined by the technique developed by Hatch and Choate (8). The diameters of particles having an average volume were 0.214 and 0.089 cm., indicating rather significant differences from the sieve sizes given above.…”

“…It seems to give fairly good results, but requires rather elaborate equipment and is time-consuming. The titrimetric procedure, involving the use of polyhydroxy alcohols and discussed in detail by several workers (8,11), is not well adapted for the rapid determination of the small amounts sometimes encountered in soil and plant analysis, because the method involves distillation which is time-consuming, and because traces of buffering substances which are difficult to remove may seriously interfere with the results.…”