By application of property of N, N'-ethylene-dianthranilic acid that reacts quantitatively with aluminum and forms white crystalline precipitate, quantitative determination of aluminum has been investigated. For the gravimetric analysis, (1) a solution containing 110mg aluminum is treated with 2g ammonium chloride, made up to 150ml with water (pH 45); this, while heating, is treated with the reagent solution, the precipitate is filtered off, dried for 1 hour at 130°C and weighed, to which multiplied with a factor 0.0569. (2) The precipitate is ignited at high temperature and determined as Al₂O₃. For the volumetric analysis, 0.56 to 2.80mg of aluminum is taken, it is precipitated similarly and filtered, the precipitate on the filter paper is dissolved by pouring 40200 ml warm 6N alcoholic hydrochloric acid and the solution is titrated with 0.1N potassium bromate, 1 ml of which is equivalent to 0.225 mg aluminum. By application of the above procedures, aluminum could be determined within th error of 2%. The presence of iron gives disturbing influence on the determination of aluminum.

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When a 0.01% ο-aminobenzaldehyde-ethylene-diimine solution in benzene is shaken with a copper containing solution of pH above 8, the copper is transfered quantitatively into the benzene layer. By application of this fact, quantitative determination of copper by a colorimetric method has been attempted. The maximum absorption of the benzene layer was at 416 mμ and there was no disturbing influence by the presence of an excess of reagent. By application of this wave length, the standard estimation curve prepared within this experimental range was found to follow the Beer's law. Ammonia alkaline solution without the presence of large amount of ammonium salt and alkaline sodium hydroxide solution containing tartaric acid can be used for colorimetric determination of copper in the pre sence of large amount of iron. There was no disturbing influence by the presence of large amount of sodium salt. The limit for determination was 1γ/ml and the procedure for colorimetric determination of copper was simple.

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Simultaneous determination of lead, cadmium, and zinc in a large amount of indium can be carried out camparatively easily by alternating current polarography, using phosphoric acid, nitric acid, ammonium nitrate, etc. as the supporting salt. It was found that the presence of halogen should be avoided as much as possible.

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In order to determine acid soluble aluminum in steel, the author studied the application of spectrographic analysis and recommended a method as follows.
1g of drillings of steel sample was dissolved in dil. nitric acid (1+1) 20cc. After 1.3g of potassium nitrate was added, the solution was condensed to about 10cc, cooled for a few minutes, diluted accurately to 10cc, and then filtered through a filter paper. A few drops of the filtrate were added into a hole (3mmφ) drilled on the surface of the graphite electrode. The graphite electrode was arced against a copper counter electrode by using an intermittent a. c. excitation.
The operation was simple and rapid. Besides, even when the sample contained vanadium or titanium, aluminum could be determined easily and as usual by this method, although chemical analysis was rather difficult in the case.
However it was necessary, and rather difficult, to prepare a lot of the same kinds of moderately soft graphite electrode, because the quality of graphite electrode was found to have a large effect on sensitivity and reproducibility of the analysis.

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After iron was extracted with methyl-isobutyl-ketone from the solution containing 6N hydrochloric acid, it could be easily determined by the flame spectrophotometry using oxygen-hydrogen flame.
Examinations of the conditions showed that the wave length at 372.0 mμ, the hydrogen pressure of 2.0 1b/in² and the oxygen pressure of 18 to 20 1b/in² were suitable. By the presented method, iron in aluminum, lead and copper could be determined down to 0.02%, and iron in lime stone, slug, and dolomite was also satisfactorily determined. By extracting iron with methyl-isobutyl-ketone from the hydrochloric acid solution, the interferences by calcium and magnesium, were elininated.

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Since dimethylformamide has shown to be a good electrolyte in the presence of a large amount of vinyl acetate, the polarographic behaviors of some impurities in vinyl acetate such as divinylacetylene, crotonaldehyde, acetaldehyde and of a few aliphatic aldehydes related with them were studied in dimethylformamide and in demethylformamide-vinyl acetate-water systems, with tetraalkylammonium salt as a supporting salt.
In the dimethylformamide system, named compounds showed characterise half wave potentials of the system. Divinylacetylene gave a two-step wave at -1.74 V and -2.22 V. As for unsaturated aldehyde, crotonaldehyde gave a one-step wave at -1.48V, and acrolein at -1.29V. Saturated aldehydes, such as acetaldehyde, n-butylaldehyde and propionaldehyde, gave a one-step wave at -2.25V. Also, in a system where D. M. F contained 75% vinyl acetate, the first wave of divinylacetylene and a reducing wave of crotonaldehyde were very clear. Although the reducing wave of saturated aldehyde is covered by the presence of vinyl acetate, a reducing wave apeared at around -1.9V with great diffusion current in the D. M. F.-water-vinyl acetate system.

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The fundamental principle of a continuous coulometric titration are that the electrolysis for generation of titrant proceeds with 100% current efficiency. In electrolysis, too large current density causes a neighbour reaction and the current efficiency falls below 100%. Accordingly, the continuous coulometric titration had been only applied to the determination of a very small concentration (00.05N) of substance.
The larger the generating electrode adopted is, the larger the electrolysis current that may be used effectively. But, in this case, the increase of the time delay of titration system causes any instability in the recording of concentration.
Accordingly, a titration system, in which the large elecrolysis current might be used and the time delay of which was minimized, was constructed and used successfully in determination of 00.2N sulfuric acid and 00.1N sodium arsenite, the concentration of which had been considered to be high for the measurement by a conventional coulometric titration.
Using the electrolyte solution in which the titration reagent had been added previously, a measurable range of continuous coulometric titration was enlarged.

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The sample solution and the electrolyte solution containing ferrous ion, generated by electrolytic reduction of ferric ammonium sulfate solution, were poured into a titration cell with a constant flow rate, mixed and reacted there. The process of the reaction was detected potentiometrically with a pair of platinum and calomel electrodes used as the sensor electrodes. The electrolysis current was so controlled that the voltage of sensor electrodes was maintained at ca. 730mV, referring the dynamic titration curve obtained experimentally.
The 03ppm residual free chlorine in city water was detemined by this method.
The relationship between the concentration of chlorine and the electrolysis current is linear and Mn²⁺, Cu²⁺, Al³⁺, Zn²⁺ and Cr(VI) contained in city water do not interfere the determination of chlorine. However, Br^-, I^- and the oxidizing substances such as Mn(VII), Ce⁴⁺, ClO₄^-, which are not contained in city water, have an influence on the measurement.
The method was tested at a water cleaning plant in Kawasaki City, and was found valuable for water-works use.
Successful results were also obtained in continuous determination of a larger quantity (0400 ppm) of residual chlorine in water by the same procedure.

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Present methods for determining small amount of sulfur dioxide in air (worker's environment) are inconvenient and time-consuming. For the rapid determination of SO₂, several granular gels which change colors when exposed to air containing small amount of SO₂ were looked for. Detector reagent consisted of purified silica gel impreg nated with I₂ solution and tetramethyl-diamino diphenylmethane was found to have the highest sensitivity in the determination of SO₂ in air. The gel was placed in a glass tube and the air sample was drawn through the tube with a constant flow rate 1cc/sec, and the quantitative estimation was possible by measuring the length of colored portion of the column. The covered range of determination were as follows:
(1) SO₂: 5300ppm when sample volume was 100ml, and feeding time 100 sec.
(2) SO₂: 140ppm when sample volume was 500ml, and feeding time 500 sec.
Mean relative error of the method was below ±5%. The proposed method and the colorimetric method was compared, and the results of actual estimations in factories by the proposed method were described.

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A polarographic method for simultaneously determining titanium and vanadium was proposed. The method is based on the measurement of polarogram in the supporting electrolyte composed of 0.1M EDTA and 0.02M sodium citrate. In this medium both ions give well-defined reduction waves, and the half-wave potentials were -0.59V vs. S. C. E. for titanium and 1.3V vs. S. C. E. for vanadium at pH 6.0.
There was a linear relationship between the concentrations of ion and the wave heights for each ion.
The synthetic samples were analyzed by this method, and satisfactory results were obtained.

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An acidic solution of hydrochloric acid or perchloric acid cotaining Fe³⁺, Al³⁺, Mn²⁺, Ca²⁺ and Mg²⁺ is adjusted to pH 2.0 by addition of ammonium acetate and the Fe is titrated with a standard EDTA solution using salicylic acid as an indicator.
The solution after determination of Fe is treated with EDTA in a slightly excess for Al, adjusted to pH 3.0, heated to boil for the reaction Al and EDTA and the excess of EDTA is titrated with a standard copper sulfate solution using PAN (α-pyridyl-β-azonaphthol) as an indicator.
The above procedure is the same as in the usual method. The solution after determination of Al is adjusted to pH 4.5, heated up to 60°C, EDTA is added in a slight excess for Mn, kept for 10 min and the excess of EDTA is titrated with the standard copper sulfate solution with PAN indicator for determination of Mn without the influence of Ca²⁺ and Mg²⁺. Although the formation constant of Mn chelate is found to be greater than that of Cu chelate, Mn²⁺ showed a red coloration with PAN and the end point of titration can be found without difficulty.
Based on the fact of determination of Mn from a solution of pH 4.5, a continuous determination of Fe, Mn, Ca by titration with EDTA becomes possible. Namely, the solution after determination of Mn is used for determination of Ca and Mg in alkaline medium as usual and the procedure is carried out as follows:
A part of solution after determination of Mn is taken, adjusted to pH 10, EDTA is added in a slight excess for total sum of Ca and Mg, the excess of EDTA is titrated with the standard copper sulfate solution and the sum of Ca and Mg is calculated. The other part of solution is treated with ammonium oxalate solution for precipitation and separation of Ca, and the solution is adjusted to pH 10 and the Mg is determined in the same way as in the detemination of the sum of Ca and Mg.
In case of dealing with a solution of Al-EDTA alone of pH 10, it caused the precipitation of aluminum hydroxide with the liberation of EDTA and the determination became impossible, but it was found that aluminum hydroxide remained unprecipitated in the presence of Fe-EDTA and Mn-EDTA and there was no disturbing influence for titration (Ca+ Mg) and Mg.

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The authors planned out a new method for the polarographic determination of zinc after dithizone extraction. After the sample is decomposed by perchloric acid, citric acid is added to mask the interfering iron etc.. Ammoniac water is added up to pH 8.2. Zinc is extracted together with copper, nickel, etc. by dithizone-chloroform solution, and separated from iron. From the extract, zinc and lead is stripped with 0.1N hydrochloric acid.
The polarogram of zinc-ammin was made out using NH₃+NH₄Cl as supporting electrolyte. The behavior of zinc during the extraction process was studied on a synthetic sample which was made by adding independently twelve kinds of elements generally contained in steel. The determination was not disturbed by lead, copper and nickel accompanied, since their half wave potentials were different.
Where the cobalt content exceeded 0.3% zinc value was read a little higher as a bit of extraction of cobalt was observed in the process of the stripping by hydrochloric acid.

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[in Japanese]

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[in Japanese]

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