A thermobalance which can operate under pressure at maximum 100 kg/cm² G and 1000°C was presented.
To measure the weight of sample under pressure, the buoyancy change caused by the change of density of gas with temperature and the change of weight of sample is the problem of great importance.
In the proposed apparatus, the apparent weight change were corrected for this buoyancy change by an electric circuit carrying out calculation.
The maximum sensitivity of the apparatus was about ±3 mg for the weight change of 1000 mg under the pressure of 80 kg/cm² G argon over the range 20800°C.
Thermograms for the thermal decomposition of a few inorganic-salts under pressure were obtained.

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Thorium reacts with morin in a weakly acidic solution to form a stable yellow complex having an absorption maximum at the wavelength of 410 mμ. The color development of the thorium-morin complex is suppressed by sulfate through the formation of sulfate complexes with thorium.
A method for spectrophotometric determination of micro-amounts of sulfate based on that interaction has been developed.
The optimum pH of the solution was 2.32.5. At this pH range, 300 μg of thorium and 500 μg of morin in 25 ml were satisfactory for the determination of mg/l of sulfate, where the decrease ofabsorbance at 410mμ (ΔA₄₁₀) was proportional to the amount of sulfate ion. A 60% ethanolic medium gave the greatest sensitivity to sulfate.
The proposed method was sensitive, manipulatively simple, and readily applicable to the determination of a large number of samples.
Sulfate ion in river waters were determined by this method with satisfactory result.

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The crude copper in molten state includes some gaseous constituents, and the ingot of the crude copper becomes porous. The test piece disk cut off from the ingot hence has many pits on its surface which give serious influences on the proportionality of X-ray intensity and the concentration of impuri-ties. But this influence of the surface state was reduced by using copper as an internal standard.
The linear calculation line was obtained in the range Sb 0.030.08% and Pb 0.1 0.3% by plotting the X-ray intensity ratio Sb-K_α/Cu-K_β (2nd) or Pb-L_β/Cu-K_β (2nd) vs. antimony or lead content. The results by this method gave good agreements with those by the chemical analysis. The time required was about 10 minutes.
The distribution of antimony and lead was also investigated by chemical analysis, optical micrography and electron probe X-ray microanalysis. The randomness of their distribution and the propriety of this method of sampling were confirmed.

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A DC arc excitation was applied to the spectrographic determination of micro amounts of Ag and Pd in pure gold.
As standard samples were used intermediate products of gold refining, of which the contents of Ag and Pd were chemically determined. One hundred milligrams of sample in a few small pieces was used in excitation.
The spectrographic conditions were : Ebert 3.4 m spectrograph, excitation voltage DC 300 V, arc current 7 amp, slit width 30 μ, electrode distance 3 mm, preburn 10 sec, and exposure 20 sec.
Linear calibration lines were obtained over the range of 430 ppm Ag and 4100 ppm Pd. Variation coefficients for Ag and Pd are 14% and, 6%, respectively.

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A ¹⁹F NMR method for the determination of boron was investigated. A boron-containing sample is treated with hydrofluoric acid, and the solution is adjusted to Ph34 by aqueous NH₃ (1 : 1). The content of boron is determined by measuring the peak area of BF₄^- signal.
The hydrolysis of BF₄^- to BF₃(OH)^- is very small, and the BF₄^- itself is a stable ion. At pH34 the exchange between F^- and BF₄^- which would lead to the broadening of signal line was not perceived.
For the determination of boric oxide in glasses, the proposed method may be rapid and simple compared with the conventional method.

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A method for the determination of small amount of arsenic in iron and steel has been presented in which arsenic is separated by co-precipitation with manganese dioxide as arsenic(V) in nitric acid or perchloric acid solution followed by reduction to metallic arsenic with stannous chloride.
The recovery of arsenic by manganese dioxide coprecipitation was higher than 98% in nitric acid and in perchloric acid but the value was lower in the solution of mixed nitric and sulfuric acid. Titanium, niobium, tantalum and zirconium interfered and were masked by ammonium difluoride.
After the separation, manganese dioxide precipitate was dissolved in hydrochloric acid and hydrogen peroxide, boiled for about 5 minutes, and reduced by heating with stannous chloride solution (dissolving 100 g of stannous chloride in 100 ml of hydrochloric acid with 2 g of tin metal) in 9N hydrochloric acid.
The metallic arsenic was dissolved in a definite amount of N/50 standard iodine solution and titrated with N/50 standard arsenous acid solution.
As little as 0.00020.02% of arsenic in iron and steel was determined with deviation less than 0.0002%.

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Chloride ion was found to be extracted into chloroform as chloropyridinemercury(II) complex, HgCl₂py₂, which then reacted with dithizone to give mercury (II)-dithizonate complex having an absorption maximum at 490 mμ. This reaction was applied to the determination of traces of chloride ion. The extraction ratio of chloride ion into chloroform was constant from slightly acidic solution (pH : 5.56.1) and the substitution reaction of the complex with dithizone in chloroform was : HgCl₂2py_2(org)+ 2H₂Dz_(org)_??_Hg (HDz)_2(org)+2pyHCl_(org), where H₂Dz represents the undissociated dithizone. A linear relationship was found between the amount of chloride ion and the absorbance at 500 mμ where the difference in absorbances between the mercury (II)-dithizonate and the reagent dithizone was largest. Ions usually accompanying with chloride ion did not interfere with the determination except bromide, iodide, thiocyanate and cyanide, which must have been removed before the determination. Less than about 20 μg (in the final solution) of chloride ion was successfully determined.

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A spectrochemical technique employing rotating electrode for the quantitative analysis of trace elements in high purity phosphorus is described. A phosphorus sample (5.0 g) is dissolved in nitric acid, and the solution is evaporated by adding 40 ppm of cobalt as internal standard. The solution thus obtained is made up to volume (50 ml ), and the aliquots are subjected to the spectrochemical determination of trace amounts of elements by high voltage spark discharge (C 0.007 μF×2, V 10 kV, L 50 μH, analytical gap 4 mm and pre-spark time 30 sec).
Limits of detection for trace elements are 0.18 ppm, and the coefficients of variation for the determination are within 5%. The proposed method is very useful for the control analysis of the preparation of high purity phosphorus.

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When a minor component is resolved poorly from the major one, it is difficult to measure accurately the area of the smaller peak overlapping the main peak.
The faint peak of tert-butanol appearing just before the main peak cf iso-propanol was recorded by the ordinary and derivative gas chromatographic method. Three modes of calibration curve, namely, (A) the plot of the derivative peak height ratio h_D1/h_D2 against the molecular ratio R_m of tert-butanol to iso-propanol, (B) the plot of the peak area ratio S₁/S₂ against R_m, and (C)the plot of the peak area S₁ against the absolute amount of tert-butanol, were constructed and compared.
It was found that with decreasing amount of butanol, the peak area became difficult to recognize and ultimately not measurable. However, the derivative peak height could be measured easily with a much better reproducibility even at the lowest concentration of butanol in sample.
The result of correlational analysis of the three calibration curves showed distinctly that, as to analytical sensitivity and linearity of calibration curve, the derivative method had distinguished superiority to the ordinary peak area method.

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Two method, methanolic bromine method and acid decomposition method, for the determination of tin oxide inclusion in Cu-Sn alloy have been presented. In order to decide the optimum condition for extracting the inclusion, the effects of decomposition temperature, concentration of bromine, etc. on the solubility (recovery) of tin oxide have been studied. The comparison of methanolic bromine method with acid decomposition method, the comparison of the oxygen content calculated from the oxide inclusion with that determined by vacuum fusion method, the structure of tin oxide inclusion, etc. have also been discussed. Tin oxide inclusion have been isolated completely as the residue from the matrix by those methods. The recomended procedures are as follows.
(1) Methanolic bromine method : 5 g of Cu-Sn alloy is decomposed with methanolic bromine (200 ml of methanol+ 20 ml of bromine) in a decomposition flask at 6065°C for 3 hr. The solution is filtered through a filter paper. The residue is washed with methanol, ignited in a nickel crucible and fused with 2 g of sodium peroxide. The melt is leached with 40 ml of 6N HCl and made up to 100 ml with 6 NHCl. An aliquot of this solution containing 10150 μg of Sn is taken into a 100 ml beaker, and 10 ml of 10% oxine solution and 10 ml of 20% NH₄Cl solution are added. The pH of the solution is adjusted to 0.85±0.01. It is transferred into a 100 ml separatory funnel, and shaken vigorously with 10 ml of chloroform for 5 min. The chloroform layer is washed with 50 ml of 1 N HCl for 2 min. and the absorbance at 385 mμ is measured against pure chloroform. The amount of Sn is determined from its calibration curve.
(2) Acid decomposition method : 4 g of Cu-Sn alloy is decomposed with 80 ml of 6N HCl and 5 mlof conc. HNO₃ (or with 80 ml of 6N HCl and 30% H₂O₂ solution) in a 300 ml beaker on a water bath.The solution is filtered through a filter paper. Theresidue is washed with 6N HCl, and treated in accordance with the above mentioned procedure (1).

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A methanolic bromine method for determination of zirconium oxide inclusion in Cu-Zr alloy have been presented. In order to decide the optimum condition for extracting the inclusion, the effects of decomposition temperature, concentration of bromine, etc. on the solubility (recovery) of zirconium oxide have been studied by the use of pure zirconium oxide and internally oxidized Cu-Zr alloy.
The zirconium oxide inclusion have been isolated completely as the residue from the matrix by this method. The recommended procedure is as follows : 25g of Cu-Zr alloy is decomposed with methanolic bromine (200 ml methano1+10 ml of bromine) in a decomposition flask at 6065°C for 3 hrs. The solution is filtered by suction through Membrane filter (UCF, mittel). The residue is washed with methanol, ignited in a platinum crucible, and dissolved with 6 ml of 60% HClO₄, 3 ml of conc. HNO₃ and 3 ml of 46% HF. The solution is evaporated to fumes of HClO₄ and made up to 100 ml with 5ml of conc. HNO₃ and water. An aliquot containing 525μg of zirconium is taken into a 50ml volumetric flask, and 25ml of conc. HNO₃, 2.5 ml of 10% urea solution and 10.0 ml of 0.05% Arsenazo-III solution are added.
It is made up to 50ml with water and the absorbance at 665 mμ is measured against water. The amount of zirconium is determined from its calibration curve.

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Coprecipitation of lead chromate and barium chromate which have the same chemical formula, MCrO₄, but belong to different crystal systems has been studied by treating an equimolar mixture of lead and barium solutions with chromic and bromate solutions at pH 4.5 to precipitate their chromates from a homogeneous solution.
Lead chromate less soluble than barium chromate precipitated predominantly, and a small quantity of barium coprecipitated. The logarithmic distribution law held for this coprecipitation system. The precipitated particles containing about 95% of lead and a few % of barium had the same morphological and crystallographic properties with pure lead chromate.

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Three standard samples varying in carbon content and three petroleum samples have been analyzed by using CHN Analyzer, Perkin Elmer Model 240.
Some statistic studies on precision and accuracy of the above analytical data were carried out in connection with those by Pregl method. As to the standard samples, the precision of the analytical results were generally satisfactory with a few exceptions while no bias was observed in all cases. As to the petroleum samples, higher hydrogen values were observed when the apparatus had been calibrated by acetanilide, but correct results were obtained by n-nonadecane which had better similarity of the hydrogen content to the petroleum samples. It has been also found that the precision of the analytical data with Perkin Elmer Model 240 depends much upon the reproducibility of the blank value that will be easily influenced by exhaustions of reduced copper (catalyst) and absorbents for CO₂ and H₂O.

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The inhibitory effect of sulfide on the formation of blue ternary complex between silver, 1, 10-phenanthroline and bromopyrogallol red was applied to the spectrophotometric determination of 0 to 1.8μg of sulfide ion in 25 ml of final solution. The precision of the proposed method was within 4.4% (coefficient of variation). The molar extinction coefficient was 1.49×10⁵ at 635 mμ.
The recommended procedure was as follows: Fifteen millilitres of the silver complex solution (containing 30 μg silver per 15 ml) was taken into a 25 ml measuring flask, and a solution (less than 10 ml) containing 0 to 1.8μg of sulfide was added to it. It is then diluted to the mark with water, and after 10 minutes, the absorbance was measured against water at 635 mμ. Gold, cyanide, iodide and thiosulfate interfered even when their amounts were one fold of sulfide.
Good results agreeing with those by p-phenylenediamine method ( JIS K 0101) were obtained for the analysis of tap water mixed with known amounts of sulfide.

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Each metel ions in mixtures of lead or bismuth and other heavy metals were examined as to be titrated together or separately by potentiometric method in many kinds of buffer solution by using the recording titration apparatus (RAT-IS) which describes the titration curve automatically for the indicationof the end point. The suitable kinds ofbuffers were disclosed for EDTA titration of lead or bismuth in mixtures with other heavy metals.

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Each metal ions in mixtures of copper, zinc or cadmium and other heavy metal were examined as to be titrated together or separately by potentiometric method in many kinds of buffer solutions by using the recording titration apparatus (RAT-IS) which describes the titration curve automatically for the indication of the end point. The suitable kinds of buffers were discloseb for EDTA titration of copper, zinc or cadmium in mixtures with other heavy metals.

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Each metal ions in mixtures of mercury, cerium or thorium and other heavy metals were examined as to titrated together or separately by potentiometric method in many kinds of buffer solutions by using the recording titration apparatus which describes the titration curve automatically for the indication of the end point.
The suitable kinds of buffers were disclosed for EDTA titration of Hg²⁺, Ce³⁺, Ce⁴⁺ or Th⁴⁺ in mixtures with other heavy metal ions.

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A rapid method for determination of organic halogens by using an improved combustion flask has been examined in which the sample is decomposed by combustion by using 10% sodium peroxide solution as the absorbent and the pH of the solution was then adjusted with concentrated nitric acid for obtaining clear end point of the titration. In the determination of iodine by the conventional method using direct addition of granulated sodium peroxide, the partly liberated iodine disturbs the color change of indicator, and it must be added just before the end point. By the proposed method, however, iodine can be determined by the same procedure with that for chlorine and bromine in the presence of the indicator from the beginning. The time required for an analysis was about 5 or 6 minutes.

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Some conditions, such as the height of light beam passing through flame and the effects of acids and coexisting elements, have been examined experimentally in case of the determination of iron by atomic absorption spectrophotometry.
Concerning the effects of coexisting elements and constituents, silicon, strontium, citric acid, tartaric acid and the sulfate of aluminum and manganese acted to decrease the absorbance of iron. But these interferences were suppressed by adjusting the height of light beam 15 to 20 mm above the burner top.

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A method for the determination of zinc in aluminum alloy by chelatometric titration after an extraction with TOPO-benzene was presented.
The sample was taken up with hydrochloric acid, hydrogen peroxide and ammonium difluoride. The acid concentration was adjusted to 1.53.0N, and ferric ion was reduced to ferrous by ascorbic acid. Zinc was extracted twice with 20 ml of benzene solution containing 0.1 M TOPO by 3 min. shaking. Zinc. in the organic layer was back-extracted with 20 ml of perchloric acid (1+15) by 1 min. shaking.
Ammonium fluoride and sodium thiosulfate were added to the back-extracted layer for masking, respectively, Al³⁺ and Cu²⁺. After the adjustment of pH with hexamine, zinc was titrated with 0.01M or 0.005M EDTA solution by using XO as an indicator. Zinc in aluminum alloy was determined in 45 min. with sufficient accuracy and reproducibility.

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An accurate method is described for the determination of plutonium in nitric acid solutions.
In this method, plutonium is directly reduced with titanous chloride solution in the mixtures of nitric acid, sulfuric acid and sulfamic acid solutions, and then titrated with a standard solution of ceric sulfate.
The titration curve is recorded by an automatic recording titrator with a combined electrode of platinum with silver-silver chloride.
Over the range from 5 to 15 mg of plutonium, the coefficient of variation was 0.50.25% for the accountability analysis of plutonium in the reprocessing of irradiated fuel.

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The analysis of ²³⁹Pu is examined by the technique of fission track method which has been used frequently for the microanalysis on uranium. The results are very consistent with expected value from the calculation, and it is revealed that fission track method can be applied conveniently for semiquantitative determination of plutonium distribution.

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A method was proposed for the gas-liquid chromatographic determination of PCMN in wettable powder and dust. PCMN was extracted with acetone and determined by gas chromatography by using a thermal conductivity detector and dibutylphthalate as internal standard. The column temperature was adjusted to 230°C and the flow rate of carrier, helium, was maintained to be 50 ml/min. PCMN was converted quantitatively to pentachlorobenzaldehyde in the gas chromatographic operation. Pentachlorobenzaldehyde initially present in commercial PCMN as an impurity caused positive error but could be eliminated by thin layer chromatographic separation before the analysis.
The results showed good agreement with those by pyridinepyrazolone method as in Table II. Those of recovery test were shown in Table I.
The calibration curve in the 0.72.3 weight ratio (PCMN/DBP) was almost linear.

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A method for the flame photometric determination of calcium in tantalum was taken in a quartz boat, covered by graphite powder and placed in a Pyrex combustion tube. The temperature was raised gradually to about 430°C in a stream of hydrogen chloride (150 ml /min) and matrix tantalum was sublimed off as tantalum chloride. The residue was taken up with hydrochloric acid and filtered. The filtrate was concentrated by evaporation, transfered to a 10 ml volumetric flask and diluted to the mark with water.
Two 10 ml aliquots of this solution were transfered to a couple of 10 ml volumetric flasks, to which were then added 1 ml of lanthanum chloride solution (10mg/ ml) and 4 ml of ethanol. A definite volume of standard calcium solution was added to one of the flasks, and calcium was determined flame-photometrically with oxy-hydrogen flame and at wavelength 422. 7 mμ by standard addition method.

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