Conditions governing a weight size determination

Direct conversion of a number count to a mass count leads to unacceptable errors. The omission of a single particle, in the largest size class (of 

Mg is the percentage by weight in the given size range is the number of particles counted in the size range.  

If it is estimated that 10% by weight of particles lie in the top size range and an accuracy of 2% is required then it is necessary to count 20 particles in the top size range. In order to cater for errors in the estimate it is suggested that 25 particles be counted. It is The number density N ) is then calculated (particles mm 2). The total count is maintained at about 700 by reducing the area examined for the smaller sizes. Briefly, the sample area required for particles of size is  

A more comprehensive mathematical procedure to determine the number of particles to be counted in order to minimize errors has been proposed by Masuda and linoya [85], This procedure mandates a much higher count than the British Standard procedure presented here [86], 

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