As it was found that rare earth elements formed a precipitate stoichiometrically combining with vanadic acid and hexamethylenetetramine, an indirect determination of rare earths was made by the estimation of vanadium in the precipitate. The composition of the precipitate was considered to be M(VO₃)₃·8HVO₃·2Hexa·4H₂O, where M=rare earth elements and Hexa=hexamethylenetetramine. The pH for complete precipitation was 35 for Pr, La and Nd, and 45 for Sm whereas the precipitation of Ce was incomplete.
The recommended method is as follows. The solution containing rare earth elements is adjusted to pH4.5 with acetic acid-ammonium acetate and ammonium vanadate about 20moles equivalent against the rare earths is added. After an addition of 10ml of 2% hexamethylenetetramine with stirring, the precipitate was separated and washed with a solution of pH4.5 containing hexamethylenetetramine.
It is dissolved in sulfuric acid and the solution is titrated with standard ferrous sulfate using diphenylamine as an indicator.
Above 1mg of rare earth element was successfully determined.

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Recent investigation has revealed that a trace of bismuth has an important effect on the nodulizing of graphite in the manufacturing of nodular graphite cast iron, and this makes it necessary to determine an extremely small amount of bismuth in pig iron and cast iron overlooked heretofore.
One g. sample is dissolved in perchloric acidnitric acid mixture and heated to white fuming. The residue is taken up in hydrochloric acid to 68N HCl and the majority of iron is removed by MIBK extraction. After the insoluble material including silica is separated by filtration, the residual iron is extracted with MIBK. The HCl layer is evaporated to dryness and the residue is dissolved in 30ml 0.3N HCl. The solution is transferred into a separatory funnel and the bismuth is adsorbed on 20ml of xylene solution of 10% Amberlite LA-1. The bismuth is liberated with 3N HNO₃, concentrated to 1ml and heated with 1ml perchloric acid
The perchloric acid is driven off, 5ml of a supporting reagent (1N HCl+N/500 HCl) is added, and the polarogram on 00.25V (vs. Hg pool) is taken. Bismuth is determined by the aid of a calibration curve preliminarily prepared. 0.0020.0025% bismuth was estimated by the proposed. method.

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Of the methods available for the determination of the gamma isomer of technical benzene hexa-chloride (BHC), polarographic analysis is one of the most convenient for routine work. However, it has been recognized that several polarographic methods give insufficient precision and reproducibility owing to the interference by other BHC isomers and high chlorinated cyclohexanes present in technical BHC.
The author was assured that polarographic wave of technical BHC stood on only three isomers of gamma, alpha, delta-BHC, provided that the electrolysis was carried out in 40% dioxane solution at pH11.0 with N/5 tetramethylammonium bromide as a supporting electrolyte.
From the results of fundamental experiments, the following procedure has been recommended: prepare a calibration curve with three isomers of gamma-, alpha, delta-BHC, and the measurement of the polarographic wave height is performed by measuring the vertical distance between the point of -1.0V and -1.2V (vs. Hg pool). The results agreed closely with those by infrared absorption method.
The proposed method is rapid, accurate and may be applicable to any technical mixture of BHC.

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Two methods for the gas chromatographic determination of hydrogen nuclear spin isomers and isotopes were investigated with special reference to their accuracy and practicability. One is based on utilizing two sorts of column packings connected in series as proposed by one of the authors {J. Phys. Chem., 65, 190 (1961)}; the first contains alumina and the second alumina coated with manganese chloride. The chromatogram may yield four peaks corresponding to p-H₂, o-H₂, HD and D₂. The other needs, two acts for the analysis. A portion of hydrogen sample is introduced on alumina column which gives rise to three peaks corresponding to p-H₂, o-H₂ plus HD and D₂ respectively. The remaining portion is introduced on alumina-manganese chloride column by which three peaks corresponding to H₂, HD and D₂ may be obtained.
From these one may readily determine the composition of four hydrogen molecular species. These two methods were applied to the quantitative analysis of hydrogen isomers and isotopes of known composition. All peaks appeared within 545 min, the composition being agreed with the expected value within ±2% accuracy.
The sample size was usually about 1ml STP. Copper oxide furnace was connected between the column and the thermal conductivity detector to convert hydrogen sample into water vapour. The temperature of the furnace had to be kept above 550°C in order to give complete combustion of hydrogen. Traces of oxygen in helium carrier were found to accumulate on the column packings kept at liquid nitrogen temperature and thereby to catalyse the para-ortho hydrogen conversion.
This unfavourable effect on the analysis of the hydrogen isomers was substantially overcome however by removing the liquid nitrogen bath occasionally from the column. Finally the method was applied to the velocity measurement of para-ortho hydrogen conversion and H₂-D₂ exchange reaction on p-benzosemiquinone ion radical stabilized on the surface of barium hydroxide octahydrate. The conversion obeyed first-order kinetics while the exchange was entirely absent, thus proving the conversion mechanism to be of magnetic character.

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Rate of precipitation and quantitative separation of nickel sulfide in solutions buffered with ammonia and ammonium nitrate wherein a stoichiometric equation CH₃CSNH₂+2NH₃+Ni²⁺→CH₃C(=NH₂)NH₂+NiS+NH₄⁺ persists have been studied over the temperature range from 50 to 80°C with the concentration of ammonia from 0.4 to 1.2M. An apparent rate equation -d[Ni]/dt=k[CH₃CSNH₂]=(k_OH{OH^-}+k_b[NH₃]) [CH₃CSNH₂] was obtained where k_OH=27.4l/mol·min, k_b=1.26×10^-2l/mol·min at 65°C and ionic strength of 0.5, and the energy of activation regarding rate const. of k was found to be 16, 000cal/mol.
It has been concluded that the precipitation reaction of nickel sulfide in ammoniacal solution is a general base catalysis by hydroxyl ion and ammonia, the experimental evidence of which rests essentially on the form of the observed rate constant, k, which is the sum of the two terms, namely, k=k_OH{OH^-}+k_b[NH₃]. This supports the present view that the acid-base reaction between thioacetamide and the bases is a rate-determining step in the precipitation of sulfide.
The sequence of the reactions is
CH₃-C-S^-=NH₂+NH₃→∧[CH₃-C_??_S_??_NH]^-+NH₄⁺ (I)
then, [CH₃-C_??_S_??_NH]^-+Ni(NH₃)m²⁺→CH₃-C-NH₂+NiS+(m-1)NH₃ (II)=⁺NH₂
The crystal structure of nickel sulfide obtained by the thioacetamide method was found to belong to Hexagonal-NiAs type by means of X-ray powder method.

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It has been said that D. T. A. data are difficult to be used in quantitative analysis, because the delicacy in setting samples as well as measuring conditions and characterisitics of each apparatus affects the records seriously.
An extensive investigation by the author on sampling and heating ratio revealed that in the case of using a 24φmm nickel block sample holder in which two symmetric sample holes of 6 φmm were drilled, a reproducible quantitative D. T. A. was available by selecting the optimum sampling condition to each form of sample with the sample mass of about 100mg and the heating rate of 10°C/min.

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A simple and extremely sensitive method of phosphorus determination with solvent extraction of heteropoly blue has been presented. It is conveniently applied to a running test solution slightly colored with the heteropoly blue to be out of a determination range in an conventional hydrazine-reduction method. It may be applied also to a solution containing colored or precipitateforming ions.
Recommended procedure: the heteropoly blue is developed by a hydrazine-reduction method {M. Miyamoto, this Journal, 11, 511 (1962).} in 25ml of an aqueous solution.
It is shaken with exact 5ml of acetophenone for about 3 min. and centrifuged for a while to separate the organic layer, the absorbancy of which is then measured within 1 hr. aginst the solvent blank at 785mμ in a 1cm cell. The range of determination is 0.1 to 4 μg P. As(III), Bi(III), V(V), W(VI), and Pt(IV) interfere.
Permissible amounts of Cu(II), Ba, Sn(II), Pb(II), Cr(III), Fe(III), Co, and U(VI) have been tabulated. As an alternative extractant, 6ml of 3-methyl-l-butanol may be used whereby reaction temperature, volume and salt concentration of the aqueous phase should be kept constant. The range of determination in the latter case is 0.2 to 6μg P.

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Separatory determination of diphenyldisulfide and thianthrene has been investigated. Diphenyldisulfide and thianthrene both develops pink coloration in conc. sulfuric acid and the absorbance at λ_max 546mμ is directly proportional to their concentrations.
On the other hand, when a benzene solution containing diphenyldisulfide and thianthrene is treated with conc. sulfuric acid, thianthrene transfers rapidly into the acid layer but diphenyldisulfide remains unextracted.
These have been applied to their determination, in which the sum of diphenyldisulfide and thianthrene in benzene solution is obtained by measuring the absorbancy at 280mμ in benzene solution and the amount of thianthrene only is obtained by measuring the absorbancy at 546mμ of sulfuric acid solution after the extraction. Diphenyldisulfide is estimated from the difference of these two values. Accurate determinations of diphenyldisulfide as little as 4×10^-5M and of thianthrene as little as 6×10^-5M were made by the proposed method. Permissible mutual ratio for the determination is from 9:1 to 1:7.

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Thallous salt gives precipitation and coloration with various ions and it has been used as a reagent for microscopic analysis.
This report deals with investigations on the volumetric method with thallous salt as the standard solution, especially suitable for determinations of molybdenum(VI), tungsten(VI), and vanadium(V) by amperometric or potentiometric titration.
Since thallous salts of molybdenum, vanadium, and tungsten had innegligible solubilities in water, the pH ranges for complete precipitation of these tallous salts were determined. Each determination was made on the acetone-containing solution, the precipitate was taken up in acid and the amount was determined by a liquid amalgam method.
For the amperometric titration, a dropping mercury electrode was used as an indicating electrode and a saturated calomel electrode as an opposite electrode.
Potentiometric titrations using various bimetal electrodes were tried, and it was found that platinum-lead amalgam for molybdenum and vanadium, and tungsten-lead amalgam for tungsten were most preferable giving satisfactory results.

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A rapid photometric method for the determination of SO₃ in cement is presented applying the thorium borate-amaranth method as follows.
The sample is dissolved in hydrochloric acid, Fe³⁺ and Al³⁺ are seperated out as hydroxide with ammonia and Ca²⁺ and Mg²⁺ are masked with maleic acid. The solution with resulting pH of 56 is shaken with the thorium borate-amaranth dye reagent for 90 seconds at liquid temperature of 14.520°C. After the extra reagent is filtered off, the absorbance is measured at 532mμ and the SO₃% is calculated from the calibration curve, where the absorbance is directly proportional to SO₃ content.
The time required for a procedure is about 30 minutes. Satisfactory precision and accuracy are obtained for the rapid analysis.

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