equivalent curve for Dye 11, E 11, indicates that the original reactive dye, Dye-X, has very little substantivity under the given conditions and has achieved its full ex- haustion of about 10% before the addition of alkali. After the addition of alkali, two new dye species begin to form. Curves FI and FII represent the increase from zero of-the covalently bound dyes I and I1 respec- tively; Dye-0-Cell. The continuation of curves E1 and E11 (beyond the 30 minute alkali addition) represent the sum total of all the colored species associated with the fiber. At 30 minutes this color is almost all Dye-X, but Dye-0-Cell and Dye-OH ap- pear gradually, until at t = 120 minutes, it is probably all Dye-0-Cell and Dye-OH. It is not possible to distinguish from the curves alone what percentages of which species of fiber color E1 and E11 represent. The figures at the right hand side of the Fig. 1 indicate: (i) the percentage of the dyes I and I1 actuallyfixed: (68%, 66%); (ii) the percentage of hydrolyzed dyes dropped with the dyebath: (16%, 25%); (iii) the percentages of hydrolyzed dye exhausted onto the fiber: (16%, 9%); Together, ii + iii indicate the percent- ages of wasted color: (32%, 34%). It is apparent that the increased sub- stantivity of Dye I over that of Dye I1 has hardly affected the overall yield of fixed dye, but has produced 7% (1 6% minus 9%) more of a product on the fiber which is moderately substantive and will have to be removed by washing. This is a distinct drawback. But, how does 66% of Dye I1 end up fixed, when its substantivity is so low before the addition of alkali? Certainly the added alkali (being an electrolyte, like