Page:Popular Science Monthly Volume 84.djvu/222

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218
THE POPULAR SCIENCE MONTHLY

WATER
By E. T. WIGHTMAN, Ph.D.
THE JOHNS HOPKINS UNIVERSITY

THALES, one of the Seven Wise Men, said:

Water is the element, the first principle of things.

There is no doubt that Thales thought he knew a great deal about water, but even the average man to-day probably thinks he knows much more. Yet, what does he know about it?

It would be difficult to overestimate its great value to the human race, and its far-reaching importance in matters scientific.

In its various forms it has been dealt with by some of the most eminent of scientists, and the subject, like the boundless ocean, is so wide that there are few branches of scientific research in which it does not claim attention.

First of all, what is its source? According to the astronomers and geologists, the earth is nothing more than a condensed and cooled portion of a vast nebula, which must have been similar to many now adorning the heavens. This nebula was a mass of self-luminous, gaseous matter, very highly heated. Of course, water, as such, could not exist in this, but was dissociated, or separated into its constituent parts, the two gases hydrogen and oxygen. Above a temperature of 2,000° C. or 3,632° F., these gases do not combine to form water, whereas the earth, in the molten, to say nothing of the gaseous condition, must have had a temperature hardly less than 6,000° O. However, the earth finally cooled sufficiently for the water to form as steam and then to condense to the liquid state.

For a long time, in fact until about 130 years ago, it was thought that water was an element. Aristotle named it as one of the four elements, earth, air, fire and water. This view of the composition of so called matter held sway for several centuries. Even after the theory was broken up, water still remained as an element. It was not until 1781 that it was found to be a compound substance. Priestly, and likewise Lavosier, showed that when hydrogen is burned, water is the outcome. The ideas of the former, however, were in conformity with the phlogiston theory which held sway at that time. By the experimentation and study of later workers on this subject, this theory was overthrown and water was proved to be a combination of hydrogen and oxygen in the proportion of two parts by volume of the former to one part by volume of the latter, or by weight, 2.016 parts of the former to 16 of the latter. The proof is as follows: Known quantities of hydrogen