Statistical Comparisons of other Isotherms to the Plot

Statistics comparing the BET, DP and x theories. Adsorption on silica used for the as plot 

For another example, the adsorption of N2 and Ar on the 25 C outgassed thoria are presented in Table 27. The advantages for these data are presented under the Standard Thoria Plots in Chapter 5, which are the stability and uniformity of this powder with this treatment, but in addition to these, the advantage is that the measurements could be performed in a very accurate and controlled gravimetric system and many data points were collected. There is still, however, the question of range selection. The fewer the data points selected for the BET and DP fit, the better the statistics should be. (After all, if one were to select two data points one would obtain a perfect fit.) A best 

These statistics are so close, at least in the selected ranges, that a definitive distinction is not possible. It is, however, possible to create a large number of equations that would fit the data very well. There are at least over a 100 isotherms listed in the literature from which one could choose. 

If one prefers to reject the theoretical basis of x theory, then the formulation as a standard curve is still very useful. As noted in the comparison to standard curves, the x function is a very good analytical form for most standard curves. Having an analytical form for the standard curve is extremely handy for both practical measurements and theoretical development. 

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