Masaakira Kamada

Spectrophotometric determination of traces of bromide based on its catalysis of the pyrocatechol violet/hydrogen peroxide reaction

A kinetic-spectrophotometric method for the determination of bromide (0.004–0.3 mg l−1) based on its catalysis of the oxidation of pyrocatechol violet by hydrogen peroxide in HCl/H2SO4 is described. The effect of bromide is greatly increased in the presence of large amounts of chloride. The relative standard deviations are 6.4 and 13% for 0.034 and 0.010 mg l−1 bromide, respectively (n = 10). Most ions commonly occurring in natural waters do not interfere except for iodide.

Nature of volcanic gases and volcanic eruption

4. Conclusion1) The chemical composition of volcanic gases emitted from fumaroles and hot springs represents their stages of the differentiation of magmatic emanation at their effusing points, although the nature of volcanic gases varies with their orifice temperatures and geological environments. Consequently, changes of the chemical composition of volcanic gases indicate the variations in volcanic activities or geological environments.As we have seen in Table 1, halogen compounds and sulfur dioxide represent the earlier stage of the differentiation of magmatic emanation. Then the ratios such as F/CO2, Cl/CO2, Cl/SO2, SO2/CO2, SO2/H2S, H2S/CO2 and CO2/N2 may be used for the detection of the leakage of magmatic emanation depending on their stage of the differentiation of magmatic emanation and their geological environments. Laboratory experiment on heat treatment of igneous rocks supported the tendency of differentiation of volcanic gases obtained from the observation of natural volcanic gases.2) Periodic variations of discharges, temperatures, and chemical compositions of volcanic gases from geysers have been fully observed over the total eruption period of geyser action. By these studies and model experiments, the time and nature of eruptions of geysers could be satisfactorily predicted.3) Radioactivity of the volcanic gases and Tn/Rn can also be used effectively for this purpose, particularly this ratio of two isotopes is very useful for the study of transportation phenomena because the half-lives of each isotope are quite different from each other.

Indirect spectrophotometric determination of traces of antimony(III) based on its oxidation by chromium(VI) and reaction of chromium(VI) with diphenylcarbazide

Abstract An indirect method for the determination of antimony(III) is described. Antimony(III) is oxidized to antimony(V) by chromium(VI) and the excess of chromium(VI) is then determined spectrophotometrically with diphenylcarbazide. Optimal conditions were established for both the determination of antimony(III) and the elimination or reduction of interferences. Antimony(III) can be determined quickly and easily in the range 0.05–5 mg l −1 ; the relative standard deviation is 2% for 1.0 mg l −1 antimony(III). The method is applicable to marine sediments and geothermal waters.

Radioactivity of volcanic gases in Japan

5) - Summary1. The radioactivity of a large number of volcanic gases from the craters, the fumaroles and hot springs in Japan is measured, and is never negligibly small, but often so large as comparable to that of the gases from the strongly radioactive mineral springs.2. The existence of many radioactive elements such as Rn, RaA, RaB, RaC, Tn, ThA and ThB is confirmed in the volcanic gases, but An, isotope of Rn and Tn, is not yet found.3. The variations of the radioactivity and the ratio (Tn/Rn) of volcanic gases are measured and the possibility for the detection of the variations of the volcanic activities is suggested.4. The excessive distribution of Rn and Tn in the gas phase of fumaroles is a common phenomenon in the most fumaroles accompanied by hot waters in Japan. In many cases, these fumarolic gases are considered as the principal source of the radioactive substances in the hot spring waters situated closely to the fumaroles.5. The mechanism of the introduction of the radioactive substances into the volcanic gases of fumaroles is discussed.The cost of this investigation was defrayed from a grant given by the Scientific Research Encouragement Grant from the Department of Education, to which the authors wish to express their thanks.

Differential determination of antimony(III) and antimony(V) by indirect spectrophotometry with chromium(VI) and diphenylcarbazide, after reduction of antimony(V)

Abstract Antimony(III) is determined indirectly through its reaction with excess of chromium(VI), the excess being quantified with diphenylcarbazide and measurement at 540 nm. Antimony(V) is reduced to antimony(III) with sodium sulfite in hydrochloric acid solution; excess of sulfite is eliminated by boiling. The subsequent determination of antimony(III) gives the concentration of total antimony, and antimony(V) is found from the difference between the results before and after reduction. Antimony in its different oxidation states can be determined in the range 0.04–0.7 mg l−1 within an error of about 10%.

Kinetic spectrophotometric determination of antimony(III) based on induced oxidation of tris(1,10-phenanthroline)iron(II) by chromium(VI)

Abstract The method involves the measurement of the extent of the induced reaction, which ceases a few seconds after initiation. Antimony(III) can be determined in the range 0.4–10 μg ml -1 . The standard deviation is ±0.25 μg. The method is applied to marine sediments.

Differentation of magmatic emanation

Chemical properties of magmatic emanation can be estimated roughly by i) volatiles from rocks by heating at various temperatures, ii) volcanic emanations, iii) residual magmatic emanations, iv) calculation from chemical equilibrium between volatile matters and magmas. Magmatic emanation is assumed to consist all of the volatile matters in magmas such asH2O, HCl, HF, SO2H2S, H2,CO 2,N2 and others (halides, etc.) at about 1200°C, although various kinds of magmatic emanations can be formed at different conditions. Magmatic emanation separated from magmas will change their chemical properties by many factors such as changes of temperature and pressure (displacement of chemical equilibrium), and reactions with other substances and it will differentiate into volcanic gases, volcanic waters, volcanic sublimates, and hydrothermal deposits (hot spring deposits).At temperatures above the critical point of water, separation of solid phase (sublimates), liquid phase, and displacement of chemical equilibrium may take place, and gaseous phase will gradually change their chemical properties as will be seen at many fumaroles. Chloride, hydrogen, andSO2 contents will gradually decrease along with lowering temperature.Once aqueous liquid phase appears below the critical point of water, all the soluble materials may dissolve into this hydrothermal solution. Consequently, the gaseous phase at this stage must have usually a little hydrogen chloride as is observed at many fumaroles. Aqueous solutions must be of acidic nature by dissolution of acid forming components, and by hydrolysis (Chloride type). When a self-reduction-oxidation reaction of sulfurous acid takes place, an aqueous solution of sulfate type will be formed. At this stage, solid phases consist of the remained sublimates which are difficultly soluble in aqueous solution, and deposits formed by reaction in the hydrothermal solutions.The gaseous phases below the boiling point of water, have usually a little water, and consist mainly ofCO2 type,H2S type,N2 type, and mixed type owing to elimination or addition of components by reactions with waters or wall rocks according to their geological conditions. Aqueous solutions which was of acidic nature must be changed into alkaline solutions by reaction with wall rocks for a long time. When the oxidation of sulfur compounds takes place, an aqueous solution of sulfate type will be formed. Hydrogen sulfide type of water will be formed by reaction of sulfides with acid waters or absorption of hydrogen sulfide. Carbonate type of water will be formed whenCO2 is absorbed. Solid phases at this stage consist usually of hydrothermal deposits except for that at solfatara or mofette.The course of differentiation of magmatic emanation could take place in more complicated ways than that of magmatic differentiation.