$($Distributions in a stirred tank$)$ Using a negat$$ve step tracer input, Cholette and Cloutier $[$Can$.$ J$.$ Chem. Eng., $37,107(1959)]$ studied the RTD in a tank for different stirring speeds. Their tank had a $30-$in$.$ diameter and a fluid depth of $30$in$.$ indide the tank. The inlet and exit flow rates were $1\mathrm{.}15$gal$//$min$.$ Here are some of their tracer results for the relative concentration, C$//$C$\_(0)($courtesy of the Canadian Society for Chemical Engineering$)$: Negative Steps Tracer Test Impeller Speed $($rpm$)$ Time $($min$)170100100\mathrm{.}7610\mathrm{.}653150\mathrm{.}6950\mathrm{.}566200\mathrm{.}6390\mathrm{.}513250\mathrm{.}5920\mathrm{.}454300\mathrm{.}5430\mathrm{.}409350\mathrm{.}5020\mathrm{.}369400\mathrm{.}4720\mathrm{.}333450\mathrm{.}4360\mathrm{.}307500\mathrm{.}4070\mathrm{.}276550\mathrm{.}3760\mathrm{.}248600\mathrm{.}3500\mathrm{.}226650\mathrm{.}329$