The following study has been made with the case in which sugar is added as a reducing agent to a glass batch containing iron oxide and an observation has been given to how the sugar works its influence upon the rate of oxidation of the iron oxide in said glass.
(A) Into a soda-lime-silica glass batch in which 2% of the lime has been replaced by equal amount of iron oxide added, as a reducing agent, sugar by increasing gradually the amounts from 1% to 5%, and the variation of oxidation of the iron oxide contained in the resultant glass.
(1) The amount of sugar added to the glass batches, variation of iron oxide in the glasses produced, and variation of the colour of glasses are tabled as follows:
It is seen that the colour of the glasses gradually tends to the greenish with the increase in amount of sugar added until it reaches dark greenish brown, while the percentage ratio of FeO/FeO+Fe₂O₃ decreases as the amount of sugar increases.
(2) Transmission curves have investigated with samples of these glasses having both sides thereof polished.
It is shown that the total transmission is lowered with increase in amount of the sugar added, the maximum transmission wave length being shifting toward the longer wave. It is also seen that the transmission curve in the ultra-violet region is well resembled to that of the carbon coloured glass. On the other hand the shortest wave length transmitting the glass advances toward the shorter wave length as the amount of sugar added is increased. However, in glasses to which much sugar have been added the total transmission have been too small and accordingly to make any exact measurement as to the shortest wave length that transmits these glasses has been unabled.
(B) By keeping constant the amount of sugar added to the glass batches as a reducing agent the iron oxide content in glass composition has been increased.
(1) The lime contents in soda-lime-silica glasses and potash-lime-silica glasses have been replaced by iron oxide one by one, and the respective batches have been melted by adding the reto 0.5% of sugar. The following table shows variation of the oxidation of iron oxide and the glass colour produced.
It has been seen that the variation of FeO/FeO+Fe₂O₃ in the glasses gradually goes higher until the ironoxide content in the glasses reaches 1%, but it rather tends declining when the content be over 1%. This may be due to that the amount of the reducing agent remains constant in spite of amounts of iron oxide in glasses are increased. As regards the colour, the soda glasses change from greenish-yellow to bluish with an increase in the iron-oxide contents, while in potash glasses they change from yellow to bluish-green.
(2) Respective transmission curves have been sought from samples of these glasses having both sides polished. In glasses small amount of iron-oxide contained the short wave length transmitting the glasses has been found little, due to the reducing agent, but in those having much of iron oxide contained it has been found that there is substantially no difference with the shortest wave length that transmits the glasses containing no reducing agent, due to the shortness of said agent.

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Two kinds of plate glass and two kinds of chemical ware glass were treated with (1) mixtures of ammonium fluoride and hydrofluoric acid and (2) mixtures of potassium fluoride (or bifluoride) and hydrofluoric acid.
The temperature, the time and the composition of the etching solution were variously changed and the influences of the each factor were examined. The suitable compositions of the etching solution for each glass were searched, the reasons of the differences of the results due to the differences of the compositions of etching solutions were discussed.
In the ammonium fluoride and hydrofluoric acid series, the concentration of them must be high to get beautiful mat surface. With concentrated solutions, good results were gained at comparatively low temperature (ca 30°C) and in short time (ca 5 min.) On the contrary, with dilute solutions, good results were difficultly gained even at high temperatures and in long time.
With fluorides of potassium and hydrofluoric acid, good results could be gained at lower concentration than the case of ammonium fluoride.
The “etch crystals” by potassium fluoride were far smaller than the etch crystals by ammonium fluoride.
With potassium fluoride and hydrofluoric acid solutions under certain conditions a networklike etched surface was gained.
When there were scratches on the glass surface the etch crystals were produced more easily along them. Generally, the etch crystals were produced more easily on the edges of the specimens than near the centres of them. And when the glass has cord or striae, in some cases the smaller etch crystals were produced at that place, on the contrary in some cases that part remained transparent. This means that the composition of the glass at that place is different from another place.

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(1) 第1報の實驗に於て效果の最も著しかつた鹽化第二鐵を硬化促進劑として用ゐ, 燒塊粉末に石膏2.5%を混和したセメントの凝結硬化中に示す温度の上昇, その軟練1:3モルタルの抗張力の軟鋼との接着力, 凝結時間及び標準軟度に依る小型耐壓力, セメントに20倍の水を加ふる時に生ずる液中のカルシウム及び第二鐵並に液の水素イオン濃度等を測定した。尚ほ他種の添加物に就ての實驗を行つた。
(2) 鹽化鐵を加へたセメントは凝結硬化に際して著しく發熱する。
(3) 鹽化鐵は軟練モルタルの折張力並に之と軟鋼との接着力を増す。鹽化鐵はセメントの凝結時間を短くする。
(4) 鹽化鐵はセメントに多量の水を加ふる時に生ずる液中の石灰を著しく増加せしめるが, pH價の増加は僅少である。此際鐵は水酸物として實際的完全に沈澱する。
終りに本研究は研究費の一部を財圖法人手島工業教育資金團の補助に依つた著者等は該財團に對して衷心謝意を表する次第である。

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