In most forms of countercurrent extraction column, the very small droplet required for rapid attainment of equilibrium, and thus for high productivity, cannot be used due to the problem of preventing it from leaking move in the wrong direction. In the case of the solid, however, for any rational size of the particle a filter will prevent its movement in any unwanted direction. Consideration of such facts led us to try to absorb water into silica gel etc., and then to use the water-saturated solid as one phase of a chromatogram, while the other is a fluid immiscible with water , while the silica simply acts as a mechanical support. to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay This type of chromatographic division is therefore based on differences in the partition between two liquid phases of the substances to be divided and not, as in all chromatograms previously described, on the differences in absorption between liquid phase and solid phase. The difficulties of using the chromatogram have been diminished when the substances to be separated are made visible by coloring. Various techniques have been used for this purpose (see Zechmeister & Cholnoky, 1936; Cook, 1941), although none of these were suited to our problems. Since the substances we wanted to separate were acids, and one of our phases is water, we were able to obtain visual evidence of the presence of any of these acids by adding a suitable indicator to the water with which the gel was saturated. In the present article we introduce an approximate theory of chromatographic separation and describe an application of the new chromatogram to the microdetermination of the top monoamino acid in protein hydrolysates. This technique is based on the distribution of acetamino acids between the chloroform phase and the aqueous phase, and replaces the macromethod described by us (Martin & Sygne,1941,1), being rapid and economical in terms of both materials and equipment. Work is progressing, using ethyl acetate as the least polar phase in the chromatogram, in separating acetyl derivatives of most other naturally occurring amino acids, and the technique promises to also be useful in similar separations of simple peptides . We would like to underline, however, that the possible fields of usefulness of the new chromatogram are by no means limited to protein chemistry. Using suitable phase pairs, many other substances should be separable. If water is suitable as one of the phases, an indicator can be used to make the separation of organic acids or bases visible. Even where this is not possible, as in the case of neutral substances, the theory set out below will allow "cuts" to be made in the known partition coefficient. In the usual adsorption chromatogram optically active adsorbents have been used for optical resolutions (see Henderson & Rule, 1937; Karagunis & Coumoulus, 1938), and in the new chromatogram resolution of racemic substances can be expected when one of the two phases is optically active (see Bailey & Hass, 1941). The mobile phase may not be liquid but may be a vapor. We show below that the contact efficiency between phases (theoretical plates per unit column length) is far better in the chromatogram than in normal distillation or extraction columns. Very specific separations of volatile substances should therefore be possible in a column in which permanent gas is flowed over gel impregnated with a non-volatile solvent in which the substances to be separated obey approximately the law of, 1937).