Variable outer radius variation of P with R

Donaghue and Bostock [63] differentiated equation (8.68) with respect to R, giving  

Slope measurements of the P-R curve permit calculation of the mass fraction oversize. 

The apparatus developed for this determination consisted of a stepped centrifuge so that the suspension is contained in a space consisting of a 

The advantage of this instrument, over the Simcar which was developed later, was that six points on the distribution curve were determined simultaneously. The main disadvantage, which prevented the centrifuge from being accepted, was loss of sediment due to movement of supernatant liquid during its withdrawal. 

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