There are very many reports of studies on refractory materials but are relatively few reports of systematic studies on refractory cements and mortars. Also, there are no definite methods of testing and standard specifications of refractory cements and mortars, without those of German engineering standards (Deutsche Ingenieure Normen, DIN). DIN 1095 and 1096 are still tentatives for refractory mortars and stamping materials of Siemens-Martins' furnace and cokes oven, and DIN 4080, 4081 and 4082 are still tentatives for testing methods, i.e., elutriating and sieving tests, melting test by prismatic piece and softening test under load of refractory mortars and stamping materials. The present authors intended to study on refractory cements and mortars, and started firstly to test systematically the refractory cements on the market. The following is the brief abstract from the Japanese communication of the preliminary study.
(1 9 samples of refractory cements were collected from the market. At first, they were analysed by the common method of total analysis and were obtained the following results.
Table 1-Results of Analysis of Chemical Compositions of Refractory cement Samples
It can be clearly seen from these results, that (a) these 9 samples can be devided in three kinds, i.e., (1) high alumina (about 60-68%) and low silica (about 29-33%) containing samples as K I, K II and T I, (2) medium alumina (about 37-47%) and silica (about 40-53%) containing samples as PE I, PE II, PY I and PY II, and (3) low alumina (about 14-25%) and high silica (about 63-75%) containing samples as T II and T III, (b) both samples K I and K II contain very small amount of loss on ignition and quite different from T I and other kinds of 6 samples, and (c) samples containing large amounts of loss on ignition are generally to be the samples of containing smaller amount of total sum, which fact is to be observed of containing some plastic admixtures, as fire clay, water glass, etc.
(2) 6 samples were tested on their specific gravities and grain distributions by sieving method. The results are shown in the table 2.
Table 2-Results of Tests of Specific Gravity and Fineness of Refractory Cement Samples
From these results, K II has the largest specific gravity, owing to the large content of alumina, and 2 samples of high silica type T II and T III have smallest values of specific gravity. The fineness or grain distribution is quite diverse, but there are generally larger amounts of coarse grain greater than 900 meshes/cm² and fine powder smaller than 4900 meshes/cm² and relatively small amount of medium grain between 900 and 4900 meshes/cm².
(3) These 6 samples of refractory cements were kneaded with amount of water to mould test pices of length: 6cm, breadth: 3cm and thickness: ca. 1cm, and tested on their drying and burning shrinkages, as following:
Table 3-Results of Test on Drying and Burning Shrinkages of Refractory Cement Mortars
(4) The authors are now further studying on various points, e. g., melting points, burning shrinkages and softening points under load 2kg/cm², corrosion actions of slag, ash, glass, etc. at high temperatures, etc. By refering these results of comparative tests of these common refractory cements on the market, it will be purposed to prepare and test some special refractory cements, especially having hydraulic property at room temperature, or so-called hydraulic refractory cements and mortar. These results will be reported in the following communications.

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The following paper deals with the preliminary experiments on the coloration of glasses by carbon, which will be studied further on.
The glasses which conform to the general molecular formula 1.3 R₂′O, R″ O, 6SiO₂ and 1.3 R₂′ O, B₂O₃, 6SiO₂, have been selected and the following two series of experiments have been carried out, the amount of the total batch being about 3.5kg.
a) The glasses have been produced by melting the batch mixtures in which the ordinary graphite content lies between 0.1% and 0.5%.
b) The glasses have been prepared from the raw batch mixtures into which 1% graphite and 1% oxidizing or reducing agents have been added respectively.
The general conclusions which have been obtained from the results of the experiments stated just above are as follows.
(1) Whne the component R″O in the glass is metallic oxide, the glass thus produced shows no colour, or even if coloured, it is very thin and weak.
The glasses of the other composition showed the colouration varying from yellow to brown according to the amount of graphite added into the batch.
(2) When the amount of graphite is too excess, the glass can not be coloured, the carbon being floated upon the molten glass or suspended in it rendering the glass greyish.
(3) It has been found that the oxidizing power of nitre is not so effective, but that of arsenic is so powerful that the yellowish or brown colour of the glass which should be rendered by graphite has throughly faded away.
The reducing action of the sugar is not so remarkable, but it has been seen that the sugar makes the glass colour somewhat deeper.

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Microscopic and X-ray investigations were made for the purpose of verifying an assumption reported in the sixth article that the minute regular crystals, which are produced when 3CaO⋅Al₂O₃ is hydrated with comparatively small amounts of water and whose ND is 1.604, and the regular crystals of 3CaO⋅Al₂O₃⋅5.8H₂O with ND of 1.605, which were obtained by Katsuzo Koyanagi during his study of the hydration of alumina cement (This Journal, 1933, 41, 118), are probably same.
The results can be abridged as follows:
(1) The various crystals of Koyanagi's 3CaO⋅Al₂O₃⋅5.8H₂O have a quite same structure according to the X-ray investigation although they have outer forms different one another. This fact together with the results of the chemical and microscopic observations indicate that the difference in the crystal forms owes to the rate of crystallization of the same compound which is affected by sorrounding conditions.
(2) The minute regular crystals of hydrated tricalcium aluminate obtained by the present authors with small amounts of water are completely same in microscopic and X-ray properties with the Koyanagi's hydrate. Their ND and lattice constant are 1.604 and 12.454 Å respectively. Their crystal growth is incomplete and such idiomorphous crystals as shown by Koyanagi must probably be obtained under definite conditions.

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