Electrolytic deposition of various metal ions from a solution containing 0.4 M sodium tartrate and 0.1 M sodium acid tartrate by the use of a platinum electrode has been investigated. The deposition potentials of these metals for cathodic deposition against saturated calomel electrode were estimated with the following result : Au + 0.50 V, Ag + 0.30 V, Hg + 0.25 V, Cu-0.30 V, Bi-0.35 V, Pb-0.50 V, Cd-0.90 V, Sb-0.75 V and Zn-1.10 V (vs. S. C. E. ). Also, electrolytic determinations of these metals were made with the use of a controlled cathode potential method, and it was found that these metals give quantitative electrodeposition, except for Au, Ag, and Hg. Similarly, electrolytic separation and quantitative determination of Cu-Bi, Cu-Cd, Bi-Cd, Cu-Pb, Pb-Cd, Cu-Zn, and Cu-Bi-Cd-Zn were carried out with good results.
Fundamental studies on the electrolysis of various metal ions in ammoniac solution have been made. The deposition potentials of these metal ions in a solution containing 1.2 N NH₄OH and 0.2 M NH₄Cl were estimated with the following results : Ag-0.05 V, Hg-0.05 V, Cu-0.45 V, Co-0.85 V, Ni-0.90 V, Cd-0.90 V, and Zn-1.40 V (vs. S. C. E. ). After confirmation of quantitative electrodeposition of these metals by controlled cathode potential electroanalysis, separation and quantitative determination of Ag-Cu, Cd-Zn, Cu-Ni, Ag-Cd, etc. were made with good results.

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Reaction between potassium dichromate solution and sodium sulfite solution has been investigated by use of potentiometric titration and photometric method. The result of potentiometric titration indicated that the percentage of reaction, on the supposition that the reaction of potassium dichromate and sodium sulfite proceeds at the molar ratio of 1 : 3, decreased with the decrease of an initial concentration of potassium dichromate and it was 16.5% when the initial concentration of potassium dichromate was 8.33×10^-6 M/l in 0.4N hydrochloric acid acidity, and 13.0% in 0.4N sulfuric acid acidity. These values showed good agreement with the experimental results of photometric method at the same initial concentration of potassium dichromate. Tests by photometric method indicated that the percentage of reaction was 100% when the reaction was carried out after previous removing of dissolved oxygen ; and the reaction of potassium dichromate and sodium sulfite proceeded at the molar ratio of 1 : 3 when there was no dissolved oxygen. Thus, it was confirmed that the decrease in the percentage of reaction with the decrease of initial concentration of potassium dichromate in the potentiometric titration was attributed to the effect of dissolved oxygen.

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Quantitative determinations of sulfides have been made using an oxidimetric standard solution of potassium ferricyanide. Titration of sodium sulfide in sodium hydroxide, sodium carbonate, or ammonia, with ferricyanide and sodium nitroprusside as an indicator gave oxidation up to sulfur. The necessary pH ranges for this titration were investigated, and it was found that quantitative oxidation could be obtained with a pH range of 10.012.0. The presence of sulfite or thiosulfate was shown to have no effect.

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An acetic acid distillation method and an acetic acid neutralization method have been investigated to find a simple and rapid method of determination of acetyl groups and C-methyl groups. In the neutralization method, an equation of regression line (Tab. 1) was sought through the use of a titrated amount, y, of standard alkali for the amount, x, of acetic acid used under various conditions. The problems of the loss of acetic acid during the removal of corbon dioxide from the distillate, and of the amount of alkali required for phenolphthalein coloration were clarified. Based on the above findings, a method of estimation of the strength of alkali standard solution for titration of acetic acid was established. A new steam distillation apparatus (Fig. 1) for acetic acid was made, and its accuracy for determination of acetic acid studied under various conditions. It was found that an accurate determination with a relative error of about 0.2 % can be made by using 1025 ml solution in the distilling flask with the addition of less than 3 ml H₂SO₄ (1 : 2) and more than 5 g anhydrous Na₂SO₄ for 10 ml solution. The values of blanks estimated under various conditions by the above method were extremely small. The total time required for distillation and titration was about 15 min. Thus the method was shown to be rapid as well as accurate.
Quantitative determinations of acetyl and C-methyl groups have been studied by the use of the apparatus described in the preceding report. The relation between the temperature and the time required for saponification of the acetyl group was clarified (Fig. 2). It was found that the time required for the saponification can be shortened to 2030 min by the use of a heating apparatus at 200250°C. Quantitative determination from phenacetin can be made with a precision of 0.14 % of the square root unbiased estimate of variance.
The Kuhn apparatus for the determination of C-methyl groups requires skill in its operation, while the determination by the use of this apparatus can be made easily, and with good accuracy, as in that of the acetyl group. Reagents are also discussed in this report. It was found that 30 % hydrogen peroxide can be used as a reducing agent for chromic acid.

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By present procedures, to determine the small quantities of aluminum in alkali products easily and accurately is impossible. The conventional gravimetric method of determining combined ferric and aluminum oxides by difference is tedious, and the obtained result is doubtful. Moreover, all of the ordinary colorimetric methods for the determination of aluminum are seriously affected by iron, small amounts of which are generally contained in a sample, and it is difficult to eliminate the effect of iron simply and completely.
The method of simultaneous spectrophotometric determination of micro quantities of iron and aluminum with oxine, which had been investigated and reported by one of the authors, has been applied and found very useful in the determination of these two metals in alkalies.
The acidified alkali sample is treated with oxine, and the pH value is adjusted to 5.05.5. Then extraction is made with exactly 10ml of chloroform, and the absorbancies of this chloroform layer are measured at 470 and 390mμ. The absorbancy at 470mμ is proportional to the amount of iron, and that at 390mμ to the sum of iron and aluminum. Hence, the amounts of iron and aluminum can be calculated from the two values of absorbancies at 470 and 390mμ.
This method is very simple and even 0.0001%, of Fe₂O₃ and Al₂O₃ in alkalies can be determined readily and accurately.

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An application of chemical analysis to small amounts of methanol and methyl acetate in vinyl acetate is difficult. An attempt has been made by the authors to utilize infrared absorption spectroscopy for this purpose, and it was found that vinyl acetate shows a comparatively weak absorption at around 3 μ. Absorption spectra through a 1 mm layer of solution were measured. By the estimation of light absorbancy at 2.78 μ and 3.37 μ, less than 2 vol % of methanol and less than 6 vol % of methyl acetate can be determined simultaneously with an accuracy of ± 0.03 vol % and ±0.2 vol %, respectively. The limit of detection is 0.05 and 0.2 vol %, respectively. This method of analysis is useful as a routine method.

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[in Japanese]

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