A rapid method of simultaneous determination of sulfur, calcium, and barium in lubricating oils by fluorescent X-ray was examined.
The result showed that the base oils in lubricating oils gave a remarkable influence, and it was removed by making the I_B-value constant as well as by using it as the internal standard. The matrix effect of sulfur was examined in its concentration of 0.3 to 3.0 wt%. Values of calcium and barium were affected by the matrix effect in the ranges of 0.023 to 0.12 wt% of calcium and 0.038 to 0.268 wt% of barium, respectively. On the contrary, sulfur was not affected by calcium and barium in their ranges described above. Consequently, calcium and barium were determined by their calibration curves prepared using the calibrated values of sulfur.
The precisions of the proposed method was comparable with that of the conventional one. The average deviations were 0.014 to 0.042 wt% for 0.32 to 3.20 wt% S, 0.000 to 0.001 wt% for 0.023 to 0.140 wt% Ca and 0.001 to 0.002 wt% for 0.038 to 0.268 wt% Ba, respectively.

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The procedure of diphenylamine sulfonate colorimetry for determining vanadium has based on the following four reactions, i. e., (1) oxidation of vanadium(IV) to vanadium(V) by permanganate, (2) reduction of excessive permanganate by nitrite, (3) decomposition of excessive nitrite by urea, and (4) coloration of diphenylamine sulfonate by vanadium(V).
The reaction between nitrite and vanadium(V), which might cause an error for determination on above process (2) was investigated in this paper. Vanadium(V) was reduced to vanadium(IV) by nitrite more easily in sulfuric-phosphoric acid solution than in sulfuric acid solution. When no urea was used, remarkable decreases of vanadium(V) concentration were observed by the addition of 88 μg of sodium nitrite in sulfuric-phosphoric acid solution and by 350 μg in sulfuric acid solution. When urea was added initially to the solution before the nitrite treatment, a considerable error for determination was caused by the addition of 1 mg of sodium nitrite in sulfuric-phosphoric acid solution, while 1.5 mg of sodium nitrite did not affect in sulfuric acid solution.
The improved procedure recommended by the authors is as follows. (1) Relatively lower concentrations of 0.3% are proper for both of potassium permanganate and sodium nitrite solution. (2) Phosphoric acid required to control the affect of iron(III) should be added after the reduction process of permanganate by nitrite.

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The method for conversion of flow rate of carrier in the elementary analysis for the most convenient driving of combustion gas has been investigated and an automatic apparatus for this purpose is presented.
An electromagnetic valve with a regulator for adjusting flow rate in which the converting action is controlled by the input signal (1) and a relay conversion system in which the flow rate is regulated by the output control of variable load and the relay acts on the input signal (2) were compared. The process (2) was more convenient for operation and the least amount of flow was obtained accurately and with ease. Also, it was convenient for making an apparatus very small and compact.
The apparatus by the second system is consisted of a conversion mechanism in which the conversion of flow rate is done by the relayed action of a micro-switch on a mortor-driven cam, a control circuit for adjusting flow rate and an estimation mechanism for indicating flow rate.
The conversion mechanism is composed of a servo-motor with a suitable time period and a nut with special abrasion surface transmitting the rotation of the motor which is contacted with a shaft fixing two cams for determination of time period and conversion.
Since the time period of the cam is variable and available for free selection, the instrument is applicable for various purposes.

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The polarographic determination of dissolved oxygen in 0.1M KCl is investigated using the convection electrode, previously reported by one of the authors. The procedure is as follows. The amount of oxygen is regulated by adding 1M Na₂SO₃ and estimated preliminarily by Winkler method. An aluminum disk of pulley-shape coated with polystyrol resins is rotated horizontally at a constant rate in an electrolytic cell. A platinum-wire micro-electrode plated with mercury is set on the side wall of the cell near an edge of the rotating disk. Current-potential curves are obtained at various conditions and compared with those of the other electrodes.
The mercury-plated convection electrode gives well-defined and more reproducible waves than the rotating platinum electrode, and also shows a limiting current about twenty-times larger than that by the dropping mercury electrode. Half-wave potentials shift to the more negative side than by the other electrodes.
The flow-rate of the solution at the surrounding of the rotating disk, which controls the limiting current, is much greater than that of the flowing solution in the inlet or outlet pipe. Hence, no change of the limiting current is observed even when the flow-rate of the solution in the pipe decreases to about one fifth. The continuous determination of dissolved oxygen can be made in rapidly flowing samples, at the rate of 200ml/ min or more.

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Atomic absorption spectrophotometric investigation of magnesium and calcium was carried out and a method was applied for the determination of magnesium and calcium in slag and the determination of magnesium in cast iron.
The absorbance for magnesium was measured at 285 mμ by using 30 mA of tube currents of hollow cathode lamp, 1.1 kg/cm² of air pressure and 0.48 kg/cm² of acetylene gas. Calcium was measured at 422 mμ by using 50 mA filament currents of hollow cathode lamp with 1.1 kg/cm² air pressure and 0.5 kg/cm² of acetylene gas.
Effects of diverse ions and acid concentrations were also examined.
Aluminum, silicon and several other ions interfered with the atomic absorption of magnesium and calcium in flame, but those interferences were all eliminated by 1500 ppm strontium in the sample solution. These fundamental results were applied for the determination of magnesium and calcium in slag.
Magnesium in cast iron was also determined by a direct addition method without any preliminary separation. The results were very accurate and highly reproducible.

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Various supporting electrolytes have been tested for simultaneous square-wave polarographic determination of trace amounts of iron and copper in highly pure substances.
Oxalic acid solution containing a small amount of sulfuric acid was found to be suitable and its fundamental studies were carried out. The peak of iron appeared at -0.21 V (vs. Hg pool) in a solution containing 0.3M oxalic acid and 0.1M sulfuric acid, and that of copper at -0.35 V (vs. Hg pool).
Calibration lines were linear in the range of 5×10^-65×10^-5M for iron and 1×10^-61×10^-5M for copper. Although 30 times as much iron than copper had no disturbing influence, the amount of copper must not exceed 4 times of iron.
Several ppm of iron and 1 ppm of copper in a reagent grade arsenous acid were accurately determined by extracting them preliminarily with sodium diethyldithiocarbamate.

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The author has determined the adequate conditions for stable color-development in the reaction of rhenium with dimethylglyoxime and stannous chloride in the rapid determination of rhenium in rhenium-tungsten alloys by dimethylglyoxime method. Analytical procedure are as follows : 7.5 ml of 30% citric acid solution is added to alkali-fused solution of sample (10ml) in a 250ml volumetric flask, followed by additions of 2.5ml of 12N hydrochloric acid solution, 6ml of 1% dimethylglyoxime solution, 5ml of 25% stannous chloride solution, and it is finally made up to 250ml with 3N hydrochloric acid. After 5 minutes, the absorbance was measured at 462mμ.
Tungsten does not interfere in the existence of citric acid, while nickel, iron and molybdenum interfere in concentration more than 2mg/250ml. Interference by iron, however, is removed by reducing Fe³⁺ to Fe²⁺ with stannous chloride. The error in the proposed method is less than ±1.0% and the method was applied for the routine analysis of rhenium-tungsten alloys.

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We have as yet very little information as to the spectrophotometric determination of scandium. {See, this Bulletin, 12, 399 (1963)}. The authors have systematically studied the spectrophotometric behavior of scandium with some triphenyl and azo dyes.
It was found that Eriochrome Cyanine R was one of the most useful reagent for the determination of scandium.
The recommended procedure for the determination is the following ;
To an aliquot of the test solution (1 to 25 μg of Sc) add 2ml of the reagent solution (1% aq. Eriochrome Cyanine R) and 0.1ml of 1.25% gum arabic, and dilute with an ammonium acetate buffer solution (pH 7.2) exactly to 25ml. After 30min. measure the extinction at the wavelength of 535mμ against the reagent solution. The method is suitable for samples containing 0.21.2 ppm of scandium.

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[in Japanese]

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