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It is a common sense for us today that water is a compound of hydrogen and oxygen.
Until about 300 years ago, however, no one had ever dreamed of it.
What we are going to show you in this Web site will be a common knowledge
among the people 200 years ahead.
But at present the number of the people who know of it is quite limited.

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Let us start with a QUIZ : What is the following diagram ?
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Check your...