The Liesegang Phenomenon and Concretionary Structure in Rocks

Abstract

THE curious formations illustrated were produced during some experiments made to support a suggestion that the Liesegang phenomenon might be attributed to adsorption (Science Progress, x., 369, 1916). The tubes contained 15 c.c. of 1 per cent, agar gel, in which small quantities of either liver of sulphur or manganese sulphate had been dissolved, and were treated with 10 c.c. of a standard solution of the other reagent. Particularly in the case of the gels containing the polysulphides, the resulting stratification differed from that hitherto observed, in that many of the zones were separated into a number of concretions, which in some instances were joined by rods to those of the succeeding zone. The concretions were all sharply defined; the indistinctness of Fig. 2 is due to their being imbedded in the gel. The peculiar structure may be due to the presence in the gel of small nuclei in the shape of deposited sulphur, or possibly to the composite character of one of the solutes. The separate spheroids, once started, would grow by adsorption in the same way as the solid strata. To determine the exact conditions of their formation requires further investigation, but it should be possible to repeat the experiment with the carbonates of calcium and magnesium.