Many workers (10, 11, 12, 13, 14) have reported results of experiments to establish that a mixing yarn CS is exactly equal to the weighted average value of the individual mixing CS values. This leads to an important inference: we can use the general equation to estimate the CS of yarns from mixings of cottons by considering any mixing fibre test value to be equal to the weighted average of the corresponding individual cotton test values. We carried out an experiment to confirm that this inference is indeed correct. We spun two cottons, one short and coarse, and the other long and fine, in isolation as well as in mixings containing varying proportions of the two. We found the CS estimates from the General Equation to be in agreement with the corresponding experimental values –Table II – 6 - ii. This is of great practical significance, as we have now a method to estimate a mixing yarn CS from fibre tests on the component cottons.