The author investigated the thermal dehydration of purified Japanese bentonites from three different origins. One of them is of a typical yellow species and the other two are of a white one. The chemical compositions are the following:
The thermal dehydration curves of each of these three samples belong to quite the same type, and a clear distinction may be made from that of other clay-like minerals, such as kaolinite, acid clays, silica or alumina gels. The curve can be cut into three distinct parts, that is, S-shaped (50-30°C), straight (100-600°C) and hook-like shaped (600-1100°C) part (Fig.)
Having discussed many known facts related to bentonites, the author can not help coming the following conclusions:
(a) In the dehydration curve, the S-shaped section corresponds to the loss of gel waters, the straight part to the dehydration of loosely fixed water of hydrated colloidal silica, and the hooklike shaped part to the so-called constitutional water of crystalline alsilicate.
(b) The empirical formulae of the ultimate particle of bentonite can be denoted as follows:
2Al₂O₃⋅(10-x)SiO₂⋅H₂O⋅xSiO₂⋅Aq.
(c) The micelles in water may presumably have a construction like this that the very thin molecularordered crystalline layers of al-silicate plate hold colloidal silica between them with ample water in common. And the highly water-imbibing property can be attributed to the hydration and diffusion powers of swarmed ions which distribute between the plates.
Temp. in °C S₅: yellow type: T₁, Or: white type

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The author re-examined the limited miscibilities of the solid solutions in the systems 3CaO⋅Al₂O₃-2CaO⋅Fe₂O₃ and 5CaO⋅3Al₂O₃-2CaO⋅Fe₂O₃, which had been left as questions in the previous reports (part III and IV), and after the more accurate knowledge of the limited miscibilities in these binary systems was obtained, carried out the study on the system 3CaO⋅Al₂O₃-5CaO⋅3Al₂O₃-2CaO⋅Fe₂O₃. The results are as follows: Fig. A. CaO-Al₂O-₃Fe₂O₃
(1) In the system 3CaO⋅Al₂O₃-2CaO⋅Fe₂O₃, the accurate value of the maximum miscibility, with which 3CaO⋅Al₂O₃ dissolves into 2CaO⋅Fe₂O₃ in its original form, could not be found, but from the results of the microscopic observations and of the determination of the free lime, the maximum miscibility of 3CaO⋅Al₂O₃ seems to be about 0.05 mol to one mol of 2CaO⋅Fe₂O₃.
(2) In the system 5CaO⋅3Al₂O₃-2CaO⋅Fe₂O₃, the maximum miscibility of 5CaO⋅3Al₂O₃ must be about 0.4-0.5 mol to one mol of 2CaO⋅Fe₂O₃. The author takes it as 0.4 mol in his future study.
(3) In the system 3CaO⋅Al₂O₃-5CaO⋅3Al₂O₃-2CaO⋅Fe₂O₃, there is such a region that is thought to consist of ferric oxide series crystals only.
All these crystals give the X ray diffraction patterns of 2CaO⋅Fe₂O₃ type. This region may be thought as the one belonging to a solid solution series with the same type lattice structure. The composition of the solid solution, having the maximum miscibility in this region, must be about approximately 6.2 CaO:2.2Al₂O₃:Fe₂O₃ (3CaO⋅Al₂O₃:5CaO⋅3Al₂O₃:2CaO⋅Fe₂O₃=2:3:5).
Fig. A is the ternary diagram of CaO-Al₂O₃-Fe₂O₃, that obtained from the above experimental results. The hatched area in Fig. A is the region of solid solutions.

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The resistance of glasses to acids and alkalis was tested by determing the weight decrease of the powdered sample after boiling with the above-mentioned reagents and filtering through a certain definite filter paper.
The compositions of the glasses tested were as follows:
(1) Na₂O, (1-x) B₂O₃, xAl₂O₃, 6SiO₂
(2) Na₂O, (1-x) B₂O₃, xCaO, 6SiO₂
(3) Na₂O, (1-x) B₂O₃, xZnO, 6SiO₂
(4) 0.5K₂O, 0.5Na₂O, (1-x) B₂O₃, xAl₂O₃, 6SiO₂
(5) 0.5K₂O, 0.5Na₂O, (1-x) B₂O₃, xCaO, 6SiO₂
(6) 0.5K₂O, 0.5Na₂O, (1-x) B₂O₃, xZnO, 6SiO₂
where x=0, 0.25, 0.5, 0.75, 1.0.
As refference, the resistance of some commercial glasses was also determined.
The acids and alkalis used were 2nH₂SO₄, 5.5n HCl, 2n Na₂CO₃, and 2nNaOH.
The resistance to sulphurie acid and hydrochloric acid was so good for all glasses that it was difficult to make a definite conclusion regarding the relation between the compositions of the glasses and the resistance of them on the basis of this experiment.
On the resistance to sodium carbonate solution, both Al₂O₃ and ZnO seemed to have good effects, but CaO had bad effect; the replacement of 0.75 molecule of B₂O₃ by 0.75 molecule of CaO made the resistance considerably poor.
On the resistance to sodium hydroxide solution, all Al₂O₃, CaO and ZnO had good effects; but, in the case of CaO, more than 0.5 molecule of B₂O₃ must be replaced to get good result.
The attacking power of sodium hydroxide solution was most severe, sodium carbonati solution the next, sulphuric and hydrochloric acid the least.

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Of all the branches of industry which have made a remarkable progress in this country of recent, Glass Industry is one of the most active. Whether handmade in a traditional fashion, or machine-made, manufacturing of glassware is certainly rising with great rapidity and today it has reached a stage that there is practically no kind of glassware which is impossible to be produced in Japan.
From its shape and also for its practical usage, glass may be classified into the following three species:
1. Hollow glass
2. Flat glass
3. Special Glass
The total amount of glassproduction of this country during the last year and the year before last reached approximately 85 million yen (£ 5 million), of this, Hollow Glass amounts to 35 million, Flat Glass, 40 million and Special Glass, 10 million Yen. And about 35 million worth of Glassware-which is 40% of the total glass production-is being exported abroad.
II. Hollow Glass.
The glass which makes bottles, table wares, food containers and illuminators are what we call Hollow Glass. more or less, it is all in a tube shape.
Among hollow-glass wares, bottles occupy majority, including beer bottles, n in ral-water bottles, sake bottles, and medical bottles. In former years bottles were all handmade, but today most of the bottles, except thing of very little demand are all-machine-made or at least semimachine made, Even table wares and food containers, if mass production is necessary are being produced by automatic machine, but those which require special finishing artifice are made by hand. The following are the main types of finishing methods of glassware: polishing, etching, cutting, engraving, and painting. The value of high-class decorated glasware is determined by the finishing workmanship. And in the field of industrial artisanship of glassware, Japan is now showing a brilliant skill and possibilities.
The kinds of glass belonging to the species of Hollow Glass are quite numerous. Unlike Flat Glass which is made in large factories-Hollow Glass is produced at middle and small sized factories For this reason, complaints of inconsistency in quality are often. heard about Hollow Glassware. For the purpose of preventing this defect and effectuating sound development of the business, various guilds have been formed. These guilds were consolidated into an Association called, the Nippon Glass Union Trade Association with its headquarters in Osaka, each guild constituting a branch. Thus at present the Association is made of 6 branches including Osaka, Tokyo, Nagoya, Hyogo, Kobe and Fukuoka. And under the official guidance of the Ministry of Commerce and Industry, each branch has a censoring office to check up on Hollow Glassware for export. The articles subject to this official examination are bottles, tableware, food container, lamp chimney, lamp shade, lamp oil pot, imitation pearl, test tube, beaker, flask and funnel, etc.
The total mount of glassware thus examined between April 1936 and March 1937 are forty million and five hundred and sixty thousand dozens, costing 12 million Yen. This is an increase by 20% over the 1936 export and 50% increase over that of 1934. Each locality in Japan boasts of certain different types of glassware of its own.
Designed for the autonomous control and the furtherance of quality of hollow glass, Nippon Glassware Exporters Association was formed in Osaka, operating for the glassware to be exported to East Dutch Indias, the Straits Settlements, and British Inidia, beginning October 10th.
III. Flat Glass.
By flat glass is meant Window Glass or Sheet Glass; polished Plate Glass; Figured Plate Glass and Wired Plate Glass.
In Japan, Window Glass was also at first manufactured by the hand cylinder process, but later this was replaced by the Machine Cylinder process. Cylinder process is a wasteful method in that it has to blow glass metal into the shape of a cylinder first aril then cut it open to make sheet glass. Later,

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