Die Impulsfestigkeit ist eine sehr wichtige Eigenschaft der keramischen Waren, besonders der Tafelgesehirre. Die bei alltäglichen Behandlungen geschehenden Zerbrechen sind allfällig beinahe auf die Wirkung dieser Impulskraft zurückzuführen. Natürlich ist die Impulsfestigkeit der Geschirre von der Dicke des Randes und des Bodens abhängig, aber wir müssen nicht vergessen der Faktor sich zu befinden, dass die Impulsfestigkeit auch von der Form gross beeiflusst wird.
Durch gewöhnliche Pendel-Impulsmaschine prüfte der Verfasser zuerst die im Nippon fabrizierten Teller, die bis Damals gesammelt worden waren. Er erhielt das Ergebniss, dass für die Impulsfestigkeit der der Boden mit dem Rand bildende Winkel eine grössere Rolle spielt. Aber das genaue Verhältniss müssen wir in noch weiterem vollständigem Versuch erwarten. In diesem Versuch prüfte er nichts anderes als einen flüchtigen Anschein der Impulsfestigkeit von Fabrikaten im Nippon.

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In the soda-lime-iron oxide-silica glasses whose general glass composition is 72%SiO₂, (12-x)% CaO, x% Fe₂O₃, 16% Na₂O, the source of iron oxide has been used ferrous oxalate, gradually changing the value of the x from 0 to 12 one by one. In such case a study has been made as to the state of oxidation of the iron oxide, and of glass color as well as transmission curves and at same time made a comparison of these changes with FA-series described in the 3rd report.
(A) An amount of FeO contained in the glass and an amount of total iron oxide as Fe₂O₃ have been obtained through analysis and the percentage ratio of FeO/FeO+Fe₂O₃ has been sought there from, which being as follows: -
From this result it has been found that the percentage ratio of the FeO/FeO+Fe₂O₃ in all glasses except FD-1 and FD-2 will be greater as amounts of iron oxide go to increase but this tendency will cease at a certain limit, whence it will gradually approach a definite value. Next comparing the said percentage ratio of FeO/FeO+Fe₂O₃ with that of FA-series it has been noted that in this FD-series it will be increased as the iron content increases while in FA-series it will be contrary to the former.
As to the colors, glasses having smaller iron content are bluish and the amounts of Fe and Fe₂O₃ increase with the increase of iron content, presenting greenish blue glasses. When the iron content is considerably increased it presents dark green color. Compared with glasses in FD-series the color of FA-series glasses are yellowish, and a comparison has been made between glasses having the same amount of iron content in both series and, in general, glasses in FD-series are deeper and darker than those in FA-series, with respect to the colors.
(B) The transmission curves have been measured. It has been found that the transmission will be smaller as iron oxide content increases. The transmission curves of glasses in the FD-series have been compared with those of the glasses corresponding to glasses in FA-series. The maximum transmission range of glasses in FD-series has been found in the side where wave length is shorter and considerably lower.
Furthermore, a comparison has been made as to the limit of wave length which transmit the glass, between glasses of both FA and FD-series. It has been known that among the glasses having smaller iron contents there is substantially no difference therebetween.
However, as the iron content increases a difference will gradually arise between the two and glasses in FD-series transmit wave length shorter than that transmitted by FA-series glasses.
As to the transmission in 700mμ the glasses in FD-series are lower than those in FA-series and the lowering degree is for greater than the difference in the visible range.

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The authors continued their previous studies I-XIV on various mixed Portland cements and here reported the further results of comparative studies on various mixed Portland cements comparing common Portland cements and the main points of the present communication are abstracted from the original Japanese paper, as follows:
(1) The strengths for longer curing ages 13, 26 or 52 weeks of dry or non-plastic mortars and wet or plastic mortars of common and mixed Portland cement samples, which were already reported in the previous reports, are tested and discussed for the characteristic points of mixed Portland cements. The mixed cements have generally smaller strengths at shorter curing ages 3 days, 1, or 4 weeks, but larger strengths at longer curing ages, 8, 13, 26, or 52 weeks than ordinary common Portland cements, owing to the larger increment of strength by the combination between lime set free from the hydration of. clinker part and soluble sillica of high siliceous admixture.
(2) Common Portland cement, obtained from clinkers containing large amount 5-10% of uncombined or free lime, are very unstable for setting and also gave unstable mortars. But it is successfully able to obtain very stable mixed Portland cements, by mixing and grinding these clinkers with high siliceous admixtures, which are obtained plentifully as “Kayohakudo”, “Yokeihakudo”, “Keisanhakudo”, etc as shown in the previous reports.
(3) Iron or ore cements of high iron oxide special Portland cement, which already reported by the present authors in the other paper (The Journal of Chemical Industry, Japan, 1935, 38, 109, 215, 726, 1457, 1592), were prepared from clinkers containing uncombined free lime 3-6%, and their mixed cements were prepared from these clinkers and high siliceous admixtures. These cements were compared on their soundness of neat cement paste by the Le Chatelier's calliper method or Bauschinger's prismatic test pieces, and their strengths by plastic mortars as before. The mixed iron cement were very stable and completely sound, owing to the combination between the free lime in the clinkers and soluble silica in the siliceous admixtures.

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