塩化ビニールを塩素雰囲気下で炭化すると, 約800℃での炭素収率は真空中のそれに比して約3倍高くなることが見出された. この値は塩化ビニールに本来含まれている炭素のほぼ100パーセントに相当する. そこで約800℃までの塩素雰囲気下における炭化過程を熱重量分析, 容積変化, 赤外線吸収スペクトル, X線測定などにより検討した.
塩素中で塩化ビニールを加熱していくと, この実験では約70℃から塩素化がおこった. 170℃以上になるとはじめより結合していた塩素が隣の水素と反応し, 塩化水素となって逸散した. しかし塩化ビニールの中には塩素に関して2種の位置が考えられる. 一つの位置にある塩素は170°-300℃の問に除去され, もう一つの位置にある塩素は約370℃以上の温度で除去される. 塩素化の過程で入る塩素は後者の位置に入ると考えられる. 以上の過程で塩素化と脱塩化水素反応が進むので, 熔融して液相を形成したり, 塩化ビニールを構成する炭素が離脱するようなことがない. こうして得られる炭素は真空中で得られるソフトカーボンに対応していわゆるハードカーボンと呼ばれるものである.

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In order to obtain high pure crystals of silicon carbide by sublimation method, action of the cavity wall made from graphite and the basic problems in this procedure have been studied. Summerized results are as follows;
(1) Some experiments were performed with changing the materials of cavity wall. It is shown that cavity wall which made of graphite and porous carbon seemed to act as pure diffusion resistor. By the use of these materials, control of growth rate of crystals is possible.
(2) In the case of porous carbon cylinder, recrystallized SiC seemed to be seperated from raw crystals.
(3) In this experiment at 2500°C, obtained crystals mainly consisted of 6H and 15R. Coalescence of these two polytypes, even in one crystal, was often observed.
(4) Temperature distribution of the growth cavity was measured. (This is shown in Fig. 4)
(5) Supersaturation in growth cavity was calculated. In this experiment, these values were in the range up to 15%. Wedge-type hexagonal crystals seemed to be grown in the higher supersaturation than 4-5%.

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Two metasilicates, Na₂O⋅2CaO⋅3SiO₂ and 2Na₂O⋅CaO⋅3SiO₂, were studied by means of thermal analysis, powder X-ray diffraction, and infrared absorption spectra.
Na₂O⋅2CaO⋅3SiO₂ shows a reversible phase transition at about 485°C. The low-temperature modification has the hexagonal primitive cell with a=10.471, c=13.174Å, Z=6 (room temperature). Above the transition temperature, however, the hexagonal cell becomes triply primitive or rhombohedral-centered, and the reflections for which the algebraic sum -h+k+l is not divisible by 3 are extinguished in the powder X-ray diffraction pattern. The cell constants at 550°C are a=10.57, c=13.24Å, Z=6, and the corresponding rhombohedral cell constants are a=7.53Å, a=89°07′, Z=2.
2Na₂O⋅CaO⋅3SiO₂ has the cubic primitive cell with a=15.10Å, Z=16. From the comparison of both X-ray diffraction patterns and infrared absorption spectra of these two metasilicates, the structure of 2Na₂O⋅CaO⋅3SiO₂ is considered to be closely related to that of Na₂O⋅2CaO⋅3SiO₂.
It was found, from the phase study on the system Na₂O⋅2CaO⋅3SiO₂-2Na₂O⋅CaO⋅3SiO₂, that solid solutions are formed between Na₂O⋅2CaO⋅3SiO₂ and Na₂O⋅CaO⋅2SiO₂. Na₂O⋅CaO⋅2SiO₂ is isomorphous with the high-temperature modification of Na₂O⋅2CaO⋅3SiO₂, and no phase transition is observed for solid solutions rich in Na₂O. Na₂O⋅CaO⋅2SiO₂ and 2Na₂O⋅CaO⋅3SiO₂ are immiscible.

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Solubility of chrysotile in the solution of various pH was measured under pressure. In the phase diagram of the MgO-SiO₂-H₂O system already determined by Bowen and Tuttle, the solubilities of silica and magnesia have been neglected up to date. However, small amount of silica (about 1×10^-3wt. %) was detected in pure water at 420°C, and solid phase of brucite equivalent to the amount of silica dissolved in chrysotile composition was precipitated.
In hydrochloric acid solution, the chrysotile was easily decomposed to magnesium chloride and silica. In the presence of the large amount of chrysotile, however, the solution became weakly acidic by the reaction of brucite in chrysotile with the acid. In this case, the ratio of magnesium to silica in the solution of near pH=6 coincided with that ratio in chrysotile, then one suitable reaction conditon for synthesis of chrysotile would be suggested.
In sodium hydroxide solution, solubility of silica from chrysotile was about one twentieth compared to that from α-quartz. From the relation of this solubility with the pH of the solution, the predominant species of silicate ion group in the solution was estimated to be (Si₅O₁₂)^4- which nearly coincided with (Si₃O₇)^- estimated by Laudise in a solution of Na₂O-SiO₂-H₂O system.

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In this investi gationthe conditions for of growth silicon carbide whiskers by vapor phase reaction are studied in detail, whiskers are prepared. The morphologies of SiC whisker obtained are described and are related to the growth of crystals.
SiC whiskers are grown under the following. conditions: concentration of SiCl₄, 3.3×10^-4 mole/min; a caluclated SiCl₄/CCl₄ molar ratio from 1.2 to 2.2; graphite substrate temperature ranging from 1300° to 1550°C; hydrogen flow rate in reaction tube of below 200cm/min.
SiC whisker deposits from this vapor phase reaction may be of two forms: the first is a colourless and needle-like deposit. The second form is a yellow and bended SiC whisker. The needle-like whiskers show straight extinction under crossed nicoles, indication that the growth direction is along the C-axis and the cleft cross section is a hexagonal. These whiskers show X-ray diffraction pattern of 2H type SiC. SiC whisker deposists form tend to a yellow and bended structure as molar ratio of SiCl₄/CCl₄ or growth temperature are raised. These whisker show X-ray diffraction pattern of β-SiC, nevertheless numbers of birefringence spots between crossed nicols. They are not entirly β-SiC. There results may suggest that the whiskers consist of α-SiC enclosed in shell of β-SiC polycrystal.
The most profuse whisker grown are found under the following conditions: SiCl₄/CCl₄ molar ratio, 1.6; flow rate of hydrogen 85cm/min; growth temperature, 1420°C. In this experiment, no growth of β-SiC whisker have been obtained.

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We studied the glass-formation range of tellurite systems containing TeO₂. The experiments were made in the same way as in previous reports on the borate, silicate and germanate systems. The crucibles employed were made of Au-alloy containing 15% Pd. Except for TeO₂, the Oxides used were of 16 kinds of a-group elements, namely K, Na, Li, Ba, Sr, Ca, Mg, Be, La, Al, Th, Zr, Ti, Ta, Nb and W, and 5 kinds of b-group elements, namely, Tl, Cd, Zn, Pb and Bi. The results of binary and ternary systems which include all the combinations of these oxides are shown in Table 1 and Fig. 1-49 and 42-73, except for the systems with a narrow glass-formation range or none at all, which systems are listed in Table 3.
According to Brady's data on the X-ray analysis of TeO₂ glass, 4 oxygen atoms are ranged around Te at a distance of 1.95 Å and two other oxygen atoms are ranged at a distance of 2.75 Å. Therefore, the coordination of the Te⁴⁺ ion lies in an intermediate state between 4- and 6-coordination. TeO₂ itself is not vitrified. In the crystal state of TeO₂, the coordination number of Te⁴⁺ is 6. If a small amount of a modifier ion is introduced, however, TeO₂ may be vitrified. In these tellurite glasses, we consider that the Te-O distance shrinks somewhat; therefore, the 4-coordination of Te⁴⁺ becomes more stable than the 6-coordination. On the other hand, there is a series of ions which have no vitrifying range in any binary system with TeO₂. It is notable that the values of their ionic radii are within a narrow rage; as the valency of ions increases, the radius range shifts somewhat to the smaller side. These facts can be explained as follows: if a modifier ion has the structure of 6-coordination and if the size of MO₆ (M=modifier ion) is nearly the same size as TeO₆, the 6-coordination state of Te⁴⁺ may be stable.
The remarkable features of the glass-formation range of the tellurite system also include the following: (1) the range of modifier ions in the tellurite system is wider than in the borate or the silicate system and (2) there is no immiscible range in the tellurite system. These properties very much resemble those of P₂O₅ systems. The first one may be explained by the electronegativity (see Table 2). The electronegativity of Te is 2.1, which is the same value as P; therefore, the O-M bond may be ionic except for small and high valent ions. The second property is probably a problem arising from the polymerization power of glass-forming oxides.
Because many oxides are classified as modifiers, according to (1), ternary systems of the tellurite are classified largely as A-type (consisting of one glassformer and two modifier components). The hatched area in Fig. 1 shows the expected glass-formation range of the A-type.
WO₃ cannot be considered to be a modifier component. In the tellurite systems generally, the glass-formation ranges of WO₃-containing systems are large very unlike those of borate, silicate, etc. According to Gelsing the coordination number of W⁶⁺ is 4 in WO₃R₂O system (R=alkali ion). However, we consider that the coordination number of W⁶⁺ is 6 in the tellurite systems, as in borate, silicate, etc. Most of the actual glass-formation ranges of WO₃ are above the A-WO₃ line (see Fig. 35-39). In these regions the network structure contains WO₃ without a modifier ions. On the contrary, the regions within the AD line contain a network of WO₃ with modifier ions.
It is difficult to consider that Nb⁵⁺ is a network-former of the 4 coordination. The hatched area of Fig. 30-34 consists of two parts. In the one Nb⁵⁺ is a modifier, while in the other Nb⁵⁺ is a networkformer of 6 coordination. The

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