[in Japanese]

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When glass is used as an insulator in the high frequency circuit, it is demanded that it should have the smallest dielectric loss which is not so seriously considered in other usages. While many interesting literatures describing about the results of measurements of the dielectric loss of several glasses commercially made, the methods of measurement, the theoretical considerations npon dielectrics, and the like, have been published, they give us poor knowledge about the relation between chemical composition and the dielectric loss of glass. The author started in this work to settle the question concerning this region in accordance with both chemical and electrical technics.
In this work, three series of glasses, i.e. R₂O-PbO-SiO₂, R₂O-CaO-SiO₂ and R₂O-B₂O₃-SiO₂ are used. The chemical compositions of these glasses are generally expressed as follows:
X K₂O
(1-x) Na₂O, z (PbO or CaO), w B₂O₃, y SiO₂ and the values of x, y, z or w are ranged as
x y z or w
R₂O-PbO-SiO₂ O-1 6-9 0.5-2
R₂O-CaO-SiO₂ O-1 6-8 1-3
R₂O-B₂O₃-SiO₂ O-1 6-9 1-2.5
For the measurement, an A. C. bridge is used, and from the values of leakance and capacity measured at 1000 cycles per second and at room temperature, the power factor and the permittivity are calculated out.
As the results indicate, the power factor attains a minimum point by the variation of x and the ratio of mols of K₂O and Na₂O in each minimum point proves nearly equal for every series of glasses under experiment.
By the variation of y, the number of mols of SiO₂, it is recognized that the same tendency of increasing of power factor and of decreasing of permittivity is available for the series of R₂O-CaO-SiO₂ and R₂O-PbO-SiO₂, and the product of power factor and permittivity shows an increasing tendency for both above series. However the effect of the corresponding variation of y for the series of R₂O-B₂O₃-SiO₂ differs from above case, and indicates some decreasing of both power factor and permittivity.
The change of z effects also the same tendency for the series of R₂O-PbO-SiO₂, and R₂O-CaO-SiO₂, and just as contrary to the effect of variation of y, in these series while the effect of increasing of w, the number of mols of B₂O₃ in R₂O-B₂O₃-SiO₂, showing the same tendency as that of y in the series.
From the results obtained, it is presumed that the effect of the basic elements such as PbO or CaO on the electrical properties of glass differs from that given by the acid components, SiO₂ or B₂O₃, and some interesting relations between chemical composition and the dielectric loss in the series of R₂O-RO-B₂O₃-SiO₂ glasses are expected.

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The authors, in continuing their previous studies, reported in the present paper the results of comparative studies on special mixed Portland cements, which were prepared by using oil shale, its spent shale or green shaly clay clay from the Fushun coal mine in Manchoukuo. The brief summaries are abstracted from the original Japanese paper, as following:
(1) Some samples of oil shale, its spent shale from the oil shale distillation plant, green shale and its calcined product were analysed on their chemical compositions, as shown in the following table 1.
Table 1. Results of Total Analyses of Oil Shale, Spent Shale, Green Shaly Clay and Its Calcined Product
(2) Spent shale and calcined green shaly clay were tested on their soluble parts, which were determined by treating with 10% NaOH and then 5% HCl solutions. This method is now in Japan applied to test pozzolanic materials of admixtures for Portland cement. The results are tabulated in the next table 2. The green shaly clay were changed its green colour to brown by calcining at different temperatures from 300°C to 1000°C, and tested systematically on its soluble parts, of which the maximum amount about 76-77% is soluble by calcining at 700-800°C for 1-2 hours.
Table 2. Results of Soluble Analyses of Spent Shale and Calcined Green Shaly Clay
It is observed from these results that green shaly clay calcined at 700-800°C for 1-2 hours contains more amount of soluble parts and more effective as admixture for Portland cement than the spent shale.
(3) Oil shale, spent shale and green shaly clay are able to be used as clayey raw material for normal Portland cement clinker. But these moterials contain a little too small amount of silica and too large amount of alumina. So that, the simple mixture of ordinary limestone and one of these materials are not suitable to make the normal Portland cement clinker, and on the countrary, special cement clinker can be easily obtained. The next table 3 shows the chmpositions of special clinkers, which were obtained from limestone and one of oil shale, spent shale or green shaly clay.
Table 3. Results of Chemical Analyses of Special Clinkers and Their Hydraulic Modulus, etc.
It is seen from these results that the special clinker has a quite different composition from the normal clinker, owing to the simple mixing of limestone and shaly material.
(4) These special clinkers can be very easily obtained by heating the raw mixtures only at 1300-1350°C for 30-60min., owing to the high percentages of alumina and ferric oxide. The next table 4 shows the results of heating tests of these raw mixtures, by comparing the amounts ef free lime and insoluble residue.
Table 4. Results of Heating Tests of Various Raw Mixtures
Samples, I₂, II₂ and III₂ of low hydraulic moduli, combine nearly completely at 1300-1350°C, being is about 100°C lower than the sintering temperature 1400-1450°C of normal Portland cement burning.
(5) Spent shale and calcined green shaly clay, which contain about 50-75% of soluble parts as above tabulated, can be used with either ordinary Portland cement clinker or special Portland cement clinker to make mixed Portland cements. The mixing Proportions are 70-50 parts of clinker to 30-50 parts of these admixtures and the mixture must be ground to fineness about 2-3% residue on 4900 meshes/cm². In the following table 5 are shown the chemical compositions of these mixed Portland cements.
Table 5. Resulte of Chemical Analyses of Mixed Portland Cements
These mixed Portland cements contain very large amount of silica (about 35-40%) and small amount of lime (about 35-40%), being considerably different from normal Portland cement. So that, these mixed cements must be called silica cement or high silica cement.
(6) These cement

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