The heat of mixing of propylene glycol and di-propylene glycol with water was measured. The results obtained for these systems were compared with each other and it was found that the oxygen atom in the ether bond of di-propylene glycol plays an important role for the acceptor of hydrogen bonding and makes a great contribution to the heat of mixing.
The electrode potential behavior of tantalum is investigated in buffer solutions initially free from the metal ions covering the pH range 1–12. A “W”-shaped EH/pH plot is obtained and the results reveal the existence of a natural passive pentoxide film overlayered with oxygen doublets. The electrode behaves within the pH range 3–7 as a metal-metal oxide electrode subject to an overvoltage of about one volt. From pH 7 to 12 the behavior is given by the system : Ta / TaO2+ yielding an equilibrium constant K=5.10−16. Anodic polarization experiments by the repetitive oscillographic method have been also utilised in buffer solutions and in other different media. The oscillograms are mostly characterised by sharp potential jumps associating the charging of the double layer, showing the decided resistivity of the surface film. The capacity of the double layer scarcely exceeds 1 μF / cm2, except in hydrofluoric acid solutions where it attains a maximum value of 30 μF / cm2.
1) The photochemical degradation of 6 nylon was investigated through the measurement of intrinsic viscosity and the amount of water-soluble material of 6 nylon taffeta irradiated for various periods of time in Fade-Ometer. 2) The intrinsic viscosity or the number-average degree of polymerization decreases rapidly at the initial stage, while the amount of water-soluble material increases approximately in proportion to the exposure time. 3) It is deduced from the relationship between the number-average degree of polymerization and the amount of water-soluble material that the molecular chain of 6 nylon is randomly split off by light. The relationship is well explained by the theory of random breaking of the polymer chain.
Dichroisms in the visible and the ultraviolet region have been determined by the microscopic method with cupric formate tetrahydrate, cupric acetate monohydrate, anhydrous cupric propionate and its mono-hydrate. The cupric formate shows an absorption band at about 38–391013/sec. which is considered to be due to the copper ion in combination with the ligands. For this band, electric vector is much more strongly absorbed along the plane of the complex than in the direction normal to the plane. The dichroism and the absorption spectrum of the cupric formate are of the same type as those of most cupric complexes involving no special effect upon the complexes. Cupric acetate monohydrate, anhydrous cupric propionate and its monohydrate show an absorption band of a new kind at about 80×1013/sec., in addition to a band at about 43×1013/sec. which corresponds to the band at about 40×1013/sec. of the cupric formate. The polarization for the band at 80×1013/sec. is the reverse of the polarization for the band at 43×1013/sec. From the appearance of the new band at 80×1013/sec. and the reversal of the polarization property with this band, it has been concluded that the cupric compounds examined in this work, except the formate, consist of dimeric molecules having a structure similar to that of cupric acetate monohydrate. It has also been shown that the water of crystallization has very little effect upon the linkages within the complex molecules. The cupric compounds, except the formate, show in organic solvents a band at 80×1013/sec., involving the dimeric molecules in solution.
The apparent vapor pressure of solid germanium dioxide, or the dissociation pressure for the reaction GeO2(c) = GeO(g)+1/2 O2(g), was measured over the temperature range 1,040 – 1,100°C by the Knudsen’s effusion method; the results are expressed by equation (4). From the free energy equation, the heat of reaction, the free energy and the entropy change of the reaction were calculated as ΔH298=121.7±0.3kcal./mol., ΔG298=101.7kcal./mol. and ΔS298=67.3 e.u., respectively. The heat of reaction is in good agreement with the value calculated from accessible thermal data. The normal entropy of solid germanium dioxide was calculated as S298=10.8±1.0 e.u., which is in agreement with the computed value obtained by Bues and von Wartenberg.
The procedure for the determination of sulfate sulfur using a new reagent, tin (II)-strong phosphoric acid, previously devised by the authors, has been extended to the determination of sulfur in other forms of inorganic compounds, e.g., sulfide ores (zinc blende, galena and pyrite), sulfides, thiosulfates, sulfites and thiocyanates. Two procedures of the analysis have been proposed by the authors : one, suitable for sulfide ores, sulfides, and sulfites, in which samples are treated directly with tin(II)-strong phosphoric acid to reduce the sulfur to hydrogen sulfide, and the other,, suitable for sulfites, thiosulfates, and thiocyanates, in which samples are previously treated with bromine water to oxidize the sulfur to sulfate, and the sulfate is reduced to hydrogen sulfide. The hydrogen sulfide evolved from the sample is absorbed in zinc acetate solution and titrated iodimetrically as usual. The rapidity and the simplicity of the original method are still retained in this case,, by which less than 30 milligrams of sulfur in the sample can be estimated within thirty minutes with good reproducibility.
L-Seryl-L-histidine and L-seryl-L-histidyl-L-leucine have been synthesized in good yields by Sheehan’s dicyclohexylcarbodiimide method. In the removal of protecting groups of O-Bz-serine derivatives by Ben-Ishai’s method, dioxane must be used as the solvent in place of glacial acetic acid. O-Bz-L- and DL-serine ester was synthesized the mild esterification condition.