The study of the “Volcanic Sublimates” observed at the orifice of active volcanoes are important to know the process of the differentiation of the magmatic emanation. So-called “Volcanic Sublimates” are, however, not always true sublimate from the magmatic emanation, but include products of reactions among volcanic gases, surface water and surrounding rocks. In a previous paper, one of the present authors reported that small amounts of fluorine and chlorine deposited on the surface of a silica-glass tube on heating the samples of igneous rocks above 800℃, and that sodium and ammonium ions were found by qualitative tests. The result suggests that a detail study on the sublimates formed in the experiments mentioned above will give exact informations about the sublimate directly derived from the magmatic emanation. In the present study, 30～50g. of finely powdered samples of volcanic rocks were heated at 1000℃ in the silica-glass tube which is evacuated to 10^-1～10^-2mmHg excluding water vapor. The sublimates deposited on the silica-glass tube were devided into several fractions with 100℃ intervals. Water soluble halogens and alkalis were determined in each fractions. Qualitative tests were also done to examine if there were some other compounds sublimed from the rock.

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We found the phenomena like dispersion of surface waves in the observation of micro-tremors carried out in December 1961. In this paper we tried whether or not we could explain the phenomena as dispersions of surface waves. Based on the underground structure determined by means of seismic exploration, various dispersion curves of surface waves with single or double superficial layer were drawn. In case of H₁ = 17.1m. H₂ = 40.0m, V_P1 = 1500m/sec., V_P2 = 2100m/sec., V_S1 = 235m/sec. V_S2 = 839m/sec., V_S3 = 1030m/sec., μ₂/μ₁ = 20.0, μ₃/μ₂ = 1.60, dispersion curves of surface waves well conform to the velocity-period relations of micro-tremors.

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The velocity of ultrasonic impulse transmission in a molten alkali (30 per cent) silicate was measured at the temperatures of 600 to 900℃. The ultrasonic wave velocity obtained was converted into the seismic wave velocity (Table 3) by the method based on the consideration of viscosity-elasticity interaction. It seems possible to investigate the elastic responce of magma with a low frequency excitation such as seismic waves, by a high frequency experiment in laboratory.

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The observation of the volcanic earthquakes occurred near the Volcano Aso and the tectonic earthquakes of near-distant was carried out by the method of a tripartite net using a magnetic tape recorder, and the wireless telemetering system by which seismic signals were transmitted from Hondo, being near the crater, to the Laboratory 6.4km apart. The seismic wave velocities for the upper layer are V_P = 2.8km/sec and V_S = 1.6km/sec, and V’_P = 5.0km/sec for the under layer. The thickness of the upper layer is at least 3.7km. The locations of source for the volcanic earthquakes originated in the Volcano Aso were determined based on the model of 2-layered structure.

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The correlation between the size and the An composition of plagioclase can be represented as to be linear by equations of the forms, Y = aX + b or log Y = aX + b, where Y is the size and X is An %. In most cases, a＞0, which are called the positive correlation. Of two positive correlation types, the curvilinear one, of which regression is figured between log Y and X, is the most essential case in any rock series. The factor responsible for resulting to the latter case is considered as fractional crystallization under the condition of steady freezing rate in light of Shimazu's physical consideration (1959) on magmatic differentiation. Another factor is also fractional crystallization with increasing rate of freezing, which might have brought a correlation in the form of the linear regression of Y to X. It is noted that the linear regression type is mostly found among the phenocrysts in calc-alkali rocks, and even in tholeiitic or alkali rocks, it is restrictively seen in groundmass minerals and microphenocrysts being smaller size than 0.3mm in length. Some other factors are accounted for such more complicated correlation types besides the positive one as the negative correlation, or the independent, between X and Y, as shown in volcanic rocks of calc-alkali series.

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The new crater of On-take Volcano, Suwanose Island, opened in Autumn, 1960. The inlanders found this new crater in January, 1961. But, this fact was not reported due to an out-of-the-way island. The present writer visited this island in August, 1963, surveyed this new crater and got some new specimens of ejectas. The new crater which is about 50m. in diameter, opened on the northeastern wall of the old beautiful cinder cone. The bottom of the new crater is filled with the black ejectas, and the eastern part, about 1m. in diameter, is seen red colour. The ejectas about 0.1m. diameter are thrown as far as 400m. All these rocks olivine augite hypersthene andesite. All past ejectas and lavas from On-take have no phenocrystic olivine. This problem should be thought not only from the crystallization of magma, but from the structure of the underground. Their chemical compositions are shown in Table 1.

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