For Zaiser and LaMer's sulfur sols, I cannot precisely determine the critical nucleus size using the COP model but can be fairly certain that it is not in agreement with the CNT prediction. Equation (1) predicts the critical nucleus size as n c,0 = 310 ± 90 thousand S 8 units, corresponding to a critical radius of 0.026 ± 0.002 µm (where the smallest radius observed by Zaiser and LaMer was 0.07 µm). The COP model approximately predicts n c,m = 18 ± 15 thousand S 8 units (see figure for precise confidence region). While this has a very high degree of relative uncertainty, it places a maximum bound on n c,m which is significantly below the CNT prediction. This implies that CNT and the COP model are incompatible for S 8 with these data. However, it is not entirely agreed upon that S 8 is in fact the soluble "monomer" species, which could introduce errors since the physical properties used in the CNT prediction were specifically for S 8 . Additionally, as previously stated, CNT is not strictly meant to hold for this process, so it is rather impressive that the most likely values agree within an order of magnitude. Whether the issue is with the soluble species or CNT, the COP model shows potential for ruling out nucleation mechanisms, especially with more data and analysis. The COP model is not significantly different from the linear model for the present data, which lack the proper range of values for accurate estimates. The linear model, i.e. the first term of (5), predicts a particle growth rate of G 0 = 98±3 million S 8 units per minute, and the full COP model predicts G m = 91±10 million S 8 units per minute. Figure plainly shows high similarity in the model predictions, which is quantitatively confirmed by the large p-value (0.68) in the F-test for an additional term. The logarithmic plot (figure ) shows a slope of approximately 1 in this range, meaning that I would need data for larger Q m to obtain an accurate estimate of n c,m . Despite the limited data, the maximum bound on n c,m still holds, which can be graphically interpreted in that the y-intercept for line B can only be so low given that I know line A (see figure ). Even when yielding the same growth rate as the linear approximation, the COP model provides further information about the critical nucleus size. The shaded regions indicate one (darker) and two (lighter) standard deviations around the best fit using the covariance within the χ 2 fit to (7).