Small test-pieces were cut from 5 brands of magnesite bricks which had previously been examined for the modulus of elasticity at low to high temperatures (this Journal, 44, 789-796, 866-871, 1396). Several tests have been made with them for spalling tendency and associated properties. Some of the important results of the tests are abridged in the Table 1.
Table 1. Some of the important results of the tests.
The results seem to justify the following conclusions:
(1) The spalling tendency of magnesite refractories cannot be correctly determined by water-quenching test because they are slaked by steam generated vigorously in the quenching.
(2) The results of the water-quenching test agree fairly well with those of the slaking test. In other words, the effect of the steam seems to be greater than that of the quenching.
(3) Most of the loss in tensile strength on water-quenching takes place at 1 or 2 cycles and that occurring at later cycles is not marked. Usual methods of comparing the tendency by the number of cycles are not right.
(4) Among air-quenching tests, the method of comparing the resistance to spalling by the loss in tensile strength is rational. However it is not suitable since the probable errors in the measurement are great.
(5) The compressive strength of magnesite refractories is often increased by the air-quenching.
(6) The probable errors of the modulus of rupture of magnesite refractories are small. The losses in the modulus on the air-quenching agree fairly well with the modulus of elasticity at high temperatures.

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The present paper deals with the investigations upon the density of the alkali-lime-silica glasses, in which the increasing amount of lime is replaced by ironoxide.
The results of experiments have shown no remarkable difference of density between the soda-and potash-glasses and a little increase of density in the lithia-glass, in which the increasing amount of lime has been replaced by ferric oxide, while they have also shown the steady increase of density of the glasses, in which the increasing amount of lime has been replaced by ferrous oxalate, especially the appreciable increase of density in the lithia-lime-silica glass.
Using the factors for density: SiO₂=2.2, Al₂O₃=2.75, CaO=5, Na₂O=3.47, given by English and Turner, and Fe₂O₃=4.8, given by English, Howes, Turner, and Winks, the following factors were obtained from the results of analysis of the series of colored glasses already published by the author: K₂O=2.88, Li₂O=3.16, and Fe₂O₃=4.8, FeO=7 for soda-and potash-glasses, Fe₂O₃=6, FeO=8 for lithia-glasses, where the relation between the percentages of the oxides, factors for density and the density of glass is as followis: S/D=pl/dl+p2/d2+………
As shown in the following table, the densities calculated by these factors are in good agreement with those obtained by measurements.
Table
Also in the series of glasses, FAN-B2, FAN-C3, FC, FAK-B2, and FAK-C3, the densities calculated by these factors have been found to be in good agreement with those obtained by measurements.

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In the system CaO-Al₂O₃-Fe₂O₃, if Al₂O₃/Fe₂O₃ molar ratio=1, the author reported in part II (This Journal, 1937, 45, 361) that in the each sample whose constitutional lime is more or less than that of 4CaO: Al₂O₃: Fe₂O₃, there must be a solid solution having a lower miscibility than 4CaO: Al₂O₃: Fe₂O₃, notwithstanding the increase or decrease of lime. In this report, in order to study more on the author's previous report (part II), the author has, by microscopic and X ray methods, examined the chemical products which exist in the fired mixtures of xCaO: Al₂O₃: Fe₂O₃ (x=3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 10).
The author has examined the final products in the samples which were made by sintering or fusing the five mixtures of 6CaO: Al₂O₃: Fe₂O₃+SiO₂ (6, 9%) and 10CaO: Al₂O₃: Fe₂O₃+SiO₂ (5, 10, 15%), for the purpose of knowing if the existence of free lime affect the final products.
The experimental results are as follows:
(1) In the fused samples, if Al₂O₃/Fe₂O₃ molar ratio=1, 4CaO: Al₂O₃: Fe₂O₃ is the solid solution having the maximum miscibility in the system CaO-Al₂O₃-Fe₂O₃. That is, when lime is more or less than 4CaO: Al₂O₃: Fe₂O₃, the miscibility of its solid solution decreases, notwithstanding the increase or decrease of lime. and makes a solid solution having a lower miscibility than 4CaO: Al₂O₃: Fe₂O₃. If lime is more than 4CaO: Al₂O₃: Fe₂O₃, it may be assumed to be a solid solution having a higher miscibility than 4CaO: Al₂O₃: Fe₂O₃, but the fact is reverse.
This is probably because free lime reacts with Al₂O₃ in 4CaO: Al₂O₃: Fe₂O₃ and makes 3CaO⋅Al₂O₃, and a ferric oxide series compound becomes lower in miscibility than 4CaO: Al₂O₃: Fe₂O₃.
(2) The sintered samples are a little different according to firing temperatures, but they have a same tendency.
(3) There is no remarkable variations between a fired sample of a high lime mixture with SiO₂ and the one without SiO₂. In this case free lime seems to react with SiO₂, and produce 3CaO⋅SiO₂, 2CaO⋅SiO₂, or CaO⋅SiO₂ in accordance with the amount of SiO₂.
(4) Ferric oxide series compound in the special cement as celite cement of Al₂O₃/Fe₂O₃ molar ratio=1, seems to be a solid solution having a slightly lower miscibility than 4CaO: Al₂O₃: Fe₂O₃.

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Continuing the previous studies on refractory cementing materials (This Journal, 1936, 44, 441; 1937, 45, 219, 447), the present authors report in the present paper the results of further studies on various samples prepared in the laboratory under the special ideas. The brief summary is abstracted from the original Japanese communication, as following:
(1) Further comparative tests of refractoriness by the ordinary method of Seger's cone and the corrosion test by addings several samples of slags, ashes, glasses, etc., were applied to the prepared samples in the former report III (loc. cit.) and the results were compared and discussed with those of common refractory cements from the market, which were already reported in the former reports I and II (loc. cit.).
(2) Two series of samples of hydraulic refractory cements (Series III: No. 7-No. 9 and Series IV: No. 10 and No. 11) were prepared under the same principle adopted in the preparation of the special hydraulic refractory cements Series I and II in the former report III, i.e., by mixing the first refractory element of high alumina content and high refractoriness and the second hydraulic element of high alumina content and strong hydraulic property in the proportions 70-90: 10-30. These samples were again exactly tested on their various important points as hydraulic refractory cement and compared to those of Series I and II and commercial samples in the former Reports:
(3) Further, the preparation of special hydraulic refractory cements were carried out, i.e., (a) Series V: No. 12-No. 13 and Series VI: No. 14-No. 16, by the proper mixing the first refractoty element of high alumina content and the second hydraulic element of also high alumina content with the third special element confering plasticity on the mixture, e.g., bentonite, and (b) Series VIII: No. 17-No. 20, by mixing as the second element 3CaO⋅5Al₂O₃(C₃A₅) of synthesized compound of highest alumina content and as the third element slaked lime Ca(OH)₂ of very fine powder. These samples were fully tested on their important properties as hydraulic refractory materials and brought the good results certifying as the superior refractory cements.
(4) The authors are now specially studying on the application of these special hydraulic refractory cements for other purposes, which will be reported hereafter in another paper (“Studies on Hydraulic Refractory Cements', Journal of Soc. Chem. Ind., Japan, 1937, 44, 422 and its Supplemental Binding, 197B).

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A new deposit of Amakusa Stone was discoverd at Fukami, south-eastern part of Amakusa in the Kumamoto prefecture and its mining has recently been carried on.
The various properties of the new stone were compared with those of the old one produced at Takahama, north-western part of Amakusa, one of the most suitable material of porcelain in our country. In this report, the descriptions are given to show that the stone is possible to use as a producing material of white wares, especially porcelain fired in reducing atmosphere.
Their chemical compositions, pyrometic cone equivalents and minerals are as follows:

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