=Types of One-bath Chrome Tannage.=--The one-bath process is simpler than the two-bath process inasmuch as only one kind of liquor is involved, viz. one in which the chromium is in the chromic state. Hence the variants of the one-bath process consist mainly of variations in the composition of this liquor. The chief point of variation is in the readiness with which chromium hydrate is adsorbed. This is determined by the extent to which the chromic salt is hydrolyzed to form the tanning sol and free acid, and by the concentration and nature of this free acid as well as of other substances. It is difficult unfortunately to express these factors in terms which are comparable under general conditions. Chromic salts are usually hydrolyzed to some extent, but this extent is very different even in water, according to the nature of the acid radical. The degree of hydrolysis is also largely affected by the extent to which the solution has been "made basic" by the addition of alkalies. By the neutralization of the free acid in this way there is further hydrolysis, the extent of which is again influenced by the nature of the acid radical involved and other dissolved substances, especially of organic matters. Again, the hydrolysis is largely affected by the concentration of the solution even when the proportions of the ingredients are constant, and this is practically important on account of the necessity for exhausting the chrome liquors economically. Nor is the matter entirely one of degree of hydrolysis, for (as we have noted in the preceding section) the electrical condition of the chroming sol is of great importance owing to the operation of the valency rule and the possibility of zones of non-precipitation. The alkaline, neutral or acid condition of the goods when first introduced has also its influence on all these points.