substances found in nature can be reduced by chemical analysis to about 70
elements, which cannot be further divided. By various combinations of
these 70 elements all the substances known to exist in the world of nature
are built up. When the inanimate body, like any other substance, is
submitted to chemical analysis, it is found that the bone, muscle, teeth,
blood, etc., may be reduced to a few chemical elements.

In fact, the human body is built up with 13 of the 70 elements, namely:
oxygen, hydrogen, nitrogen, chlorine, fluorine, carbon, phosphorus,
sulphur, calcium, potassium, sodium, magnesium, and iron. Besides
these, a few of the other elements, as silicon, have been found; but they
exist in extremely minute quantities.

The following table gives the proportion in which these various elements
are present:

Oxygen 62.430 per cent
Carbon 21.150 " "
Hydrogen 9.865 " "
Nitrogen 3.100 " "
Calcium 1.900 " "
Phosphorus 0.946 " "
Potassium 0.230 " "
Sulphur 0.162 " "
Chlorine 0.081 " "
Sodium 0.081 " "
Magnesium 0.027 " "
Iron 0.014 " "
Fluorine 0.014 " "
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