The improving experiments were made on clay diaphragm. Methods of increasing permeability and relation between permiability and electrical resistance are described.

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Investigations were made in a practical porcelain kiln about the influence of the following conditions on the temperature of end point of SK IO:
I various methods of cone-placing into “cone pat”
II differences of the placing-depth of cone

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Each 66 batches in the systems silica-feldspar-dust and silica-soda-feldspar-dust, and 69 batches in the system Hodogaya sand-soda-dust were fired to 1410°C to find the fields of satisfactory glass with results as follows
1. The batches in the system silica-feldspar-dust are too refractory to give seedless glass by the firing. Moreover, the utilization of the Cottrell cement dust is only 20-30%
2. The glasses made of quartz sand, soda ash, feldspar and the dust are not devitrified. The field of faultless glass is pretty wide and the utilization of the dust amounts to 50% in the system.
3. Many batches in the system Hodogaya sand-soda-dust give faultless glasses. However, the utilization of the dust is only 25% since the sand contains much alumina.
4. In short, satisfactory glasses can be made of the dust, soda ash and sand. The sand may be pure or impure. The sand of Hodogaya is a tuff. Its analyses are: silica 70.74, alumina 12.27, ferric oxide 2.94, lime 1.69, magnesia 0.72, potash 4.00, soda 3.81, loss on ignition 4.04. The dust contains 2.5% of ferric oxide and therefore can not be used for the manufacture of colorless glass.

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The authors report in continuing their previuos studies on mixed Portland cements, the further results of comparative studies on special mixed Portland cements. The following summaries are abstracted from the original Japanese paper.
(1) Several sorts of admixtures, i.e., spent shale from oil shale industry, natural slliceous earths of “Keisan-hakudo”, “Yokei-hakudo”, “Kayo-hakudo”, calcined product of green shale from Fushun in Manchoukuo, etc., which had been already used by the present ahthors in the foregoing reports (this Journal, 1934, 42, 273, 629 and 688), were mixed with quick lime or slaked lime and Portland cement clinker in several proportions-Clinker: Siliceous Admixture: Limes-50-60: 20-30: 10-20, and ground to special mixed Portland cements.
(2) These special mixed Portland cements were tested on their specific gravities, apparent densities, setting times, chemical compositions, etc., and the results are tabulated in the following tables 1 and 2.
These special mixed Portland cements have considerably smaller specific gravities and apparent densities and higher voids than common Portland cement. The setting times are not so retarded by siliceous admixtures, owing to the addition of lime.
Mixed Portland cements contain large amount of insoluble residue in hydrochloric acid. The amounts of total lime are considerably smaller than those of common Portland cement, but the content of free lime in the special mixed Portland cements is very large 7-10%, owing to the addition of lime in the form of slaked or quick lime.
(3) These cement samples were tested on their compressive and tensile strengths of 1:3-cement-sand mortars by the method in the “Japanese Engineering Standards” for Portland cement (JES 28) or blast furnace alag cement (JES 29, or so-called “dry mortar” testing method. The authors are, on the other hand, studying for these years on the so-called “plastic mortar or wet mortar” testing method, which was already reported in the foregoing reports (loc. cit.), and applied to compare the present samples. From these results it was confirmed that these special mixed Portland cements harden quite well to high strengths, owing to the addition of lime in suitable amount.
(4) The coefficient of expansion or contraction during hardening (3 days, 1, 4, 8 or 13 weeks) was tested by using prismatic (4×4×20cm) test pieces of plastic mortar of these cement samples and Bauschinger's tester for expansion or contraction The present samples of special mixed Portland cements gave nearly equal or rather better results than common Portland cement.
(5) The rapid decresse of free lime in neat cement hardened for geveral weeks was confirmed by the free lime determination of Lerch and Bogue's method. Further, the expansion or contraction of these plastic mortar test pieces (4×4×20cm prisms) during the storage in several salt solutions (10% solutions of Na₂SO₄, MgSO₄, NaCl, MgCl, etc.) are now carrying on, which will behereafter reported in next reports.

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