(1) Absorption spectra of several chromic complexes were measured and it was found that the spectrochemical series is coincident with that for cobaltic complexes. (2) From the spectrochemical series was discussed the stability of the chromic complexes and some of the methods of preparation were explained. (3) All the chromic complexes have the first and the second bands. [Cr(NH3)5NCS] (NCS)2 has another band in addition, which is due to the group M←N=C (M= a metal-ion of any kind and valency). [Cr(NH3)2(NCS)4]NH4 and [Cr(NCS)6]K3 have four bands each, the first, the second, the special and the third. The special bands are due to the same origin as that of [Cr(NH3)5NCS]X2 and the third bands are attributed to trans-pairing of the anions. (4) Chromate ion, a quadri-coördinate complex, has not the first band, but the second and the third, as could be expected from the author’s hypotheses. (5) Absorption spectra of polynuclear compounds may be analysed into those of component complex radicals. For example [Co(NH3)5CrO4]Cl has three bands, of which one is the first band of the sexa-coördinate cobaltic complex and the other two are mainly the second and the third band of quadri-coördinate chromate radical. The second band of the former is almost entirely covered by the second band of the latter.
(1) The formation of silver chromate bands in silicic acid gel which was made by a usual method, has been described. (2) By this procedure, the concentration of chromate is regulated at will, and distinct banding is formed. (3) The hydrogen ion concentration of the gel has a profound influence on the formation of rhythmic bands of silver chromate. (4) Dhar and Chatteriji’s theory and the membrane theory are not applicable.
(1) The formation of rhythmic precipitate of calcium phosphate in a silicic acid gel was described. (2) The formation of this rhythmic precipitate was strongly affected by the hydrogen ion concentration of the gel. (3) The effects of the concentrations of inner and outer electrolytes, and gel on this rhythmic precipitate, were studied. (4) When the concentration of the inner electrolyte (CaCl2), was sufficiently great, no diffusion of the outer electrolyte into the gel took place but reversely calcium salt diffuse into the outer electrolyte solution and dendrities were formed in the outer solution. (5) The effect of the existence of a third substance in the gel and in the diffusing electrolyte, were also investigated. The existence of it in a diffusing electrolyte had almost no influence but the existence in a gel had some effects, especially in the case where bromide and iodide of potassium were used as the third substance.