The integral equation representing the thickness of the diffusion layer surrounding a spherical electrode is derived; upon solving this equation, the formula for the polarographic diffusion current is obtained. It becomes clear that the Ilkovic theory is not right because of its ignorance of the curvature of drop and that our revised equation can elucidate many oscillographic recordings of the polarographic current-time curves.
The differential equation representing the distribution of the depolarizer in the vicinity of dropping mercury electrode was integrated and the formula for the polarographic diffusion current was derived, which is identical with the equation obtained, as reported in our previous paper, in another way. Several experimental results were found to be in accordance with this equation; it may be said that our improved theory is not only the denial of the Ilkovic theory but also at the same time inclusive of the old theory.
(1) Cuprimetric amperometry using cupric sulfate as a standard solution was introduced in the determination of copper, zinc and magnesium. (2) Oxine, benzoinoxime or other organic reagents were used as intermediate reagent in this titration, so on the other hand, some organic substances would be determined by this method. (3) The procedure is simple and sensible to 10−4 mol Cu per liter, if suitable measures are taken.
A definition of the linear boundary tension of the two-dimensional film was conceived, which corresponds to the surface tension in the three-dimensional system. The physical meaning of this conception was investigated according to the classical Gauss theory. A rough estimation of this value was made for the surface film of myristic acid.
The molecular arrangements in liquid state may be characterized by assignement of the number of nearest neighbors on each molecule, and distances between two nearest neighbors. The assumption is made on the distribution of distances r between the two nearest neighbors which does not take a definite value as in the crystalline state but is distributed over the region of [r(1+δ), r(1−δ)]. The partition function and state equation are deduced under these assumptions using proper values of δ expected by X-ray diffraction on liquid argon. The critical constants for a simple liquid are determined which agree well with experimental values. The condition for the equilibrium between liquid and solid crystalline states is obtained on the basic assumptions that the essential differences of liquid and solid states consist in the difference of values of δ and the number of nearest neighbors around each molecule. The calculated melting temperature, volume and entropy inerements by fusion and pressure dependences of these fusion parameters agree well with experimental values.
The solubility of zinc oxalate has been reported by Kunschert (7×10−5 mol/l. at 25°) or F. Kohlrausch (4.2×10−5 at 18°), but, from the viewpoint of the relations between solubility and co-precipitation phenomena, it would be greater than their values, perhaps about 1.1∼1.6×10−4 mol/1. at room temperature. Measurements showed the solubility of zinc oxalate, of which composition was ZnC2O4·2H2O, to be 1.2×10−4 mol/l. at 20° ±0.05°. This is almost the same with the result obtained by Scholder, Gadene and Niemann (1.36×10−4 mol/l. as 18°) but further details are not clear. By the relations between solubility and co-precipitation phenomena, a presumption or investigation of solubility may be possible; namely, it may be determined by the use of the transition point of adsorption and occlusion of foreign ions (about 2×10−4 mol/l. at 20°). Needless to say, the formation or treatment of precipitate should be done under the same condition. The study on a mechanism for the adsorption or Balarew’s occlusion phenomena is in progress.
In part I, a simple method for isolating vitamin B12 concentrate was studied. In part II, (A) was decided to be a prosthetic group in natural (B) molecule biochemically, and the biosynthesis of (B) from synthetic (A) could be attained successfully.
The reduction wave of titanic ion in sulfuric acid medium was investigated in order to give some experimental supports to the theoretical results on the irreversible wave which were derived from the standpoint of chemical kinetics. The Kalousek’s method was used to test the reversibility of the reduction process of titanic ion at the dropping mercury electrode, and it was found that this process proceeds irreversibly. From the constancy of the halfwave potential, which is independent of the concentration of titanic ion, and from the linear relation between log I⁄(Id−I) and V, which were proved by the experiments, it can be said that the theoretical equation (2) explains the feature of the irreversible reduction wave such as that of titanic ion. Furthermore, the effect of the foreign electrolytes on the half-wave potential was measured, on which some discussions were carried out.
The polarographic reduction wave of nickel thiocyanate complex has been studied for the purpose of clarifying the reduction mechanism of the complex. The current-voltage curves of the complex were measured in media of KSCN-KCl and KSCN-KNO3. In the medium of KSCN-KCl, the reduction wave involved the kinetic current as well as the diffusion current, when the concentration of potassium thiocyanate was less than 0.2 M. The relation of log I⁄(Il−I) and V held a straight line, but its slope was not in accord with the value expected from the reversible reduction. From these experimental results and the polarograms obtained with the Kalousek’s method, the reduction of the complex was confirmed to proceed irreversibly at the dropping mercury electrode. The redaction mechanism of the complex and the number of thiocyanate ions coordinated to the centered metal ion in the supporting electrolytes containing various concentrations of potassium thiocyanate were estimated from these experimental results, when the theoretical consequence for the activation-controlled reduction of the complex ion reported in the previous paper was applied.