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Chapter 4　The necessary condition to keep bubbles
　　　　　　　　in the water

4.1　Effects of calcium ion for the production of the bubble
4.1.a　The existence of calcium ion that is detected by electrode reaction
　　　　 in carbonated water
　The processing of electrolysis was carried out on the carbonated water that was mixed with egg shells of calcium carbonate (CaCO3) by using high conductive charcoal electrodes. As a result, white material appeared on negative electrode by the electrode reaction as shown in Fig.20.

　　　　　　
　Fig.20　An electrode changes by electric current in the carbonated water with calcium carbonate.

When it exchanges the polarity of the carbon electrodes, the white material transfers it to the electrode of negative of the opposite side. The white material transfers it to the negative electrode again, when the direction of electric current is opposite again. Thus, the existence of calcium ion in carbonated water was detected by an electrode reaction of carbon.
　
　　 　　　　　{ Ca²⁺ + 2(OH)^-1} + 2CO2}　 ⇔ 　 CaCO3 + H2CO3　　　　(4.1)

　The calcium carbonate (CaCO3) is produced, if calcium atom is included in carbonated water (H2O + CO2). The calcium carbonate exists as limestone. Here, if free carbon atom is produced by oxidation of iron atom in carbonated water, it bonds to calcium atom and calcium carbide (CaC2) is produced. The calcium carbide reacts with water and it produces acetylene. Acetylene dissolves in water a lot. The dissolved acetylene becomes materials of organic substance. Those organic materials contribute to improve the strength of membrane. The bubble that increased strength is useful to check the nature of bubble.

　　　　　　CaC2 +　2H2O →　Ca(OH)2 + C2H2　 　　　　　　　(4.2)

4.1.b　 Effects of calcium carbonate (CaCO3) to the iron carbide bubble
　Variations of bubbles in the carbonated water that was mixed with the iron powder and calcium carbonate 　Photographs of the bubbles those were produced in the carbonated water with iron powder and eggshell are shown in Fig.21. The bubbles with double layered complex structure were formed.


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