The authors, in continuing their previous studies, reported in the present paper the further studies on fine refractory and electric insulating material “steatite”. The results were reported in Japanese, which are here briefly abstracted, as following:
(a) The effects of serveral plastisers on moulding, shrinkages of drying and burning, strengths, densities, etc., were systematically studied and the following results were obtained.
Table 1. Results of Comparative Studies on Effects of Various Plastisers (I)
* These specimens cracked in water and could not be tested on strength
It is clearly seen that sodium silicate and borax have no good effects on burning and other physical properties of steatite.
(b) F. Reinhard (Tonindustrie-Zeitung, 1932, 56, 323) reported that alkali silicate or chloride has good effect on to produce magnesium orthosilicate (2MgO⋅SiO₂) and to make good refractories. Hautefeuille (Ann. Chim. Phys., 1865, 4, 175) also reported that magnesium chloride has the same effect. The next table shows the results of studies on the effects of addition of magnesium chloride, which are better than those of sodium silicate and borax shown in the above table 1.
Table 2. Results of Comparative Studies on Effects of Various Plastisers (II)
It is seen from these results that magnesium chloride gave slightly good effect.
(c) Nextly, it was studied that the relation between the compressive strength of the products and the moulding pressure, the amount of moulding water. The results were tabulated in the following table 3.
Table 3. Relations between Moulding Pressures, Amounts of Moulding Water, etc. and Compressive Strengths of Steatite
From these results, it is clear that the compressive strength of the products depends li early on the moulding pressure, and the greater the moulding pressure is, the better the physical strength of the steatite. Relating to the amount of moulding water, E. A. Schoenberg (Elektrochem. Zeitschrift, 1933, 23, 545) reported on the dry moulding (Trockenpressung). The authors studied also on this point, which will be reported hereafter.
(d) Compressive strengths of the specimens during heating at high temperatures (600°C and 10000C) were tested by the small cylindrical test pieces (Dia: 2cm and Length: 2.5cm) and compared the results with those of chamotte refractory materials (S. Nagai and S. Mannami, this Journal, 1930, 38, 788). The compressive strengths of steatite at high temperatures (600°C, 1000°C, etc.) were lower than that at the room temperature, this fact being quite contrary to that of chamotte refractories, as shown in the following table 4.
Table 4. Results of Compressive Strength Testing at High Temperatures
(CL-211 was the sample moulded by 2% solution od magnesium chloride)
The steatite has far greater compressive strengths than those of chamotte refractories and it must be tested on at higher temperatures, which is now being studied and will be reported hereafter.
(e) Spalling test was carried out by treating the small cyliindrical test pieces (Dia: 2cm and Length: 2.5cm) heating at 1200C for 30 minutes, throwing into cold water, and then compressive strengths, densities and porosities were compared to those before heat treatment. The results are shown in the following table 5.
Table 5. Results of Spalling Tests of Steatite
From these results, it can be clearly seen that compressive or transverse srength decreases about 50-60% by heating at 1200°C for 30 minutes and quick cooling, and densities and porosities increase in every cases.
The authors are now further studying on various points, e.g., change of molar ratio (MgO/SiO₂) of steatite by adding magnesia or silica, thermal expansion, electrical properties, etc., which will be reported in the following reports.

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1 第1報の合成物中3CaO・SiO₂ 1800℃燒成物粒状部, 同燒結部, 2CaO・SiO₂ 1700℃燒成物, 3CaO・2SiO₂ 1475℃燒成物塊状部, 同ダスト, 並にβ及γ2CaO・SiO₂を得んが爲に2CaO・SiO₂燒成物を再加熱し1000℃より急冷又は徐冷せる物につきてX線的研究を行へり。
2 3CaO・SiO₂ 1800℃燒成物粒状部は純3CaO・SiO₂なり。 同燒結部はα2CaO・SiO₂と3CaO・SiO₂との混合物なるが如し。
2CaO・SiO₂ 1700℃燒成物はα2CaO・SiO₂にして3CaO・SiO₂に酷似せるもその廻折強度多少異なる。 該燒成物を再熱し1000℃より急冷すればγ及β2CaO・SiO₂を生成す。 徐冷せる場合にはγ2CaO・SiO₂の量多し。 而してα, β及γ2CaO・SiO₂はX線的に酷似せり。
3CaO・2SiO₂ 1475℃燒成物塊状部は純3CaO・2SiO₂に近く, 其ダストは3CaO・2SiO₂の1475℃に於ける解離に依て生ぜるα2CaO・SiO₂が主としてγ形に變化し, 之に3CaO・2SiO₂を混有せるが如し。
CaO・SiO₂ 1500℃燒成物は純αCaO・SiO₂なり。
3 從來發表せられたる3CaO・SiO₂は著量のα2CaO・SiO₂を混有せる疑あり。 2CaO・SiO₂のβ→γ轉移はα→βに比して急速なるが如く純β形を得ること困難なり。 從來の發表によるβ2CaO・SiO₂試料が充分純粹なりしやは疑はし。 γ形に就ても同樣なり。

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In continuing the previous study, the author reports in the present paper, on the comparison of common and damp-preventing paper bags. In this study, one common paper and 4 damp-preventing paper bags were used. That is, (A) 5 fold bag of common paper, (B) 5 fold bag with a sheet of asphalt paper, coated one-side, (C) 5 fold bag with 2 sheets of asphalt paper coated one-side, (D) 4 fold bag with a sheet of asphalt paper, coated both-sides, (E) 4 fold bag with 2 sheets of asphalt paper, coated both-sides.
The Portland cements, packed in these bags were stored in a ordinary store house for 4 months from the beginning of October, 1933 to the end of January, 1934.
The Tests of the stored cement were carried out after 2, 3 and 4 months.
In conclusion, the author determined that 4 fold bags with one or two sheets of asphalt paper, coated both-sides, obtained good results.

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