This report is continued from the last report in which a metallic powder or reducing salt has been added to glass batches containing iron oxide and melted.
(a) Glass melted by adding aluminium powder to a base glass batch in such proportions as 0.1, 0.5, 1.0%.
(b) Glass melted by adding aluminium powder to a base glass batch in which 1% of lime has been replaced by iron oxide, in such proportions as 0.1, 0.5, and 1.0%.
The transmission curves of these glasses have been measured. The shortest wave length that transmits them is in general reduced as the amount of aluminium powder added is increased, and the colour of the glass becomes greyish, accordingly a total transmission becomes smaller.
(c) Glass melted by adding to a base glass batch some stannous chloride in such proportions as 1, 4 and 8%.
(d) Glass melted by adding stannous chloride to a bese glass in which 1% of lime has been replaced by iron oxide, in such proportions as 1, 2, 4, 6 and 8%.
The transmission curves of these glasses have been measured. It has been found that the limit of wave length that transmits these glasses tends to shift toward short wave length as the amount of stannous chloride added increases, while the wave length that shows a maximum transmission tends to shift toward the blue in spectrum. These transmission curves intersect somewhere between 480 and 520.
As a result of this study it is found that the color of the glasses will be yellowish as the amount of zinc, magnesium added is increased. This seems to be that it must have reduced to colloidal iron rather than ferrous oxide. Aluminium turns to greyish while stannous chloride becomes bluish which is the color presented by ferrous oxide. In either case the amount of ferrous oxide is increased and that of ferric oxide is reduced in the glass.

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Thermal decompositions of the raw materials of glass, were studied with a thermobalance.
With certain batches, the decrease of weight due to the liberation of gaseous components were determined after heating at 700°, 800° and 900°C for 2 hours. The amounts of alkali extracted by hot water were measured on the same samples.
Batches, whose compositions were (Na₂ or K₂) CO₃, 0.5 (Ca or Mg) CO₃, 3 SiO₂, gave off almost all the carbon dioxide contained in them below about 900°C.
When 1/4 part of (Na₂ or K₂) CO₃ was replaced by the equivalent amount of (Na or K) NO₃, the liberation of gas from the batches was remarkablly accelerated, and the amount of alkali extracted by hot water was decreased at the same time, namely, the reaction was acceleratrd at least below about 900°C

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Recently there are many reports of studies on Japanese bentonite (e. g., Uchida, This Journal, 1933, 41, 181; 1934, 42. 65; 1935, 43, 21; Journ. Soc. Chem. Ind. Japan, 1935, 38, 1170, 1174; R. Isomatsu, This Journal, 1935, 43, 742; Journ. Soc. Chem. Ind., Japan, 1935, 38, 395; etc.). The present authors commenced the studies on effects of mixing bentonite to common Portland cement and reported some results in the present Japanese communication, which are briefly abstracted, as following:
(1) The two samples of bentonite from Niigata Prefecture were analysed by the methods of total analysis and soluble analysis, the latter being treated with 10% NaOH and then 5% HCl solutions on water bath. The results are shown in the following tables 1 and 2.
Table 1-Results of Total Analysis of Bentonite Samples
These bentonite samples contain not so much amounts of soluble components, silica, alumina, etc.
(2) By adding 5, 10, 15% of these bentonite samples to two samples of common Portland cement, the setting times of the cement were seen, the one retarded and the other accelerated.
(3) Two samples of clinker of common Portland cement and these two bentonite samples were mixed in proportions 90:10, 80:20 aud 60:40, two series and six samples of common and mixed Portland cements were prepared and tested on their chemical compositions, specific gravities, setting times, etc. The effect of addition of bentonite on setting time was seen to be retarding both initial and final setting times.
(4) These two series of cement samples were tested on their hardened strengths of cement-sand mortars by both of non-plastic and plastic mortars. Too much mixing of bentonite (e.g., 30-40%) does not give good results, showing the bentonite to be unsuitable as the common admixture.
(5) The plasticity of these mixed cements in pure cement paste was comparatively tested by falling cylinder of Vicat's tester degree of flow by a small flow table, Emley's plasticimeter defined in A. S. T. M. Designation: C6-31 for the hydrated lime for structural purposes, etc. Mixing about 20-40% of bentonite increased considerably the plasticity, which is seen to be suitable for the manufacture of plastic cement.
This study is now further being continued on every points, which will be reported in the future reports.

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[in Japanese]

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