2i8 THE POPULAR SCIENCE MONTHLY 



WATER 



By E. T. WIGHTMAN, Ph.D. 



THE JOHNS HOPKINS UNIVERSITY 



rpHALES, 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 por- 

 tion of a vast nebula, which must have been similar to manv now adorn- 

 ing 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 ele- 

 ments, 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 like- 

 wise Lavosier, showed that when hydrogen is burned, water is the out- 

 come. The ideas of the former, however, were in conformity with the 

 phlogiston theory which held sway at that time. By the experimenta- 

 tion and study of later workers on this subject, this theory was over- 

 thrown 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 hvdrogen- 



