Page:Popular Science Monthly Volume 84.djvu/230

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226
THE POPULAR SCIENCE MONTHLY
 
Per Cent.
Bacon 22
Eggs 65
Butter 11 to 16
Richest Milk 87
Cucumbers 97
Salmon 75
Beef 73
Cabbage 89
Potatoes 75
Cheese 25 to 50
Strawberries 90
Apples and Grapes 80
 

It would take volumes to tell of all the effects of water as a dynamic agent in geology—of the action of frost, of percolating waters, of rain, of waves, of rivers, glaciers, lakes, oceans, subterranean waters, etc., of all these and more on the exterior and interior of the earth. As justice can not be done to any one of these topics in a few words, they can only be mentioned here.

The prime importance of water to chemical reactions has already been spoken of above, but in conclusion, one or two examples will help to further show how really essential it is.

Concentrated sulphuric acid and metallic sodium will react with the most explosive violence if brought together in the presence of only a trace of water, but if proper precautions are taken to exclude every particle of moisture, drying them first and then bringing them together as quickly as possible, there will be no reaction whatever. The fuming of hydrochloric acid and ammonia in the presence of each other is proverbial in the chemical laboratory. They combine to form ammonium chloride, which appears in the form of a white cloud. Here again there is no combination, if the two are perfectly dry. Soda and tartaric acid (both solids) can be intimately mixed together, in solid form, without undergoing any reaction. But as soon as water is added, a tremendous effervescence takes place.

Many other cases might be cited, but these, as well as what has gone before, will, I hope, give some idea, at least, of the all importance of this wonderful yet common substance.