18 CHEMICAL COMPOSITION OF HUMAN BODY. 



CHAPTER II. 



CHEMICAL COMPOSITION OF THE HUMAN BODY. 



THE following Elementary Substances may be obtained by 

 chemical analysis from the human body : Oxygen, Hydrogen, 

 Nitrogen, Carbon, Sulphur, Phosphorus, Silicon, Chlorine, 

 Fluorine, Potassium, Sodium, Calcium, Magnesium, Iron, and, 

 probably as accidental constituents, Manganesium, Alumin- 

 ium, Copper, and Lead. Thus, of the sixty-three or more 

 elements of which all known matter is composed, more than 

 one fourth are present in the human body. 



Only one or two elements, and in very minute amount, are 

 present in the body uncombined with others ; and even these 

 are present much more abundantly in various states of combi- 

 nation. The most simple compounds formed by union in 

 various proportions of these elements are termed proximate 

 principles ; while the latter are classified as the organic and the 

 inorganic proximate principles. 



The term organic was once applied exclusively to those 

 substances which were thought to be beyond the compass of 

 synthetical chemistry and to be formed only by organized or 

 living beings, animal or vegetable ; these being called organ- 

 ized, inasmuch as they are characterized by the possession of 

 different parts called organs. But with advancing knowledge, 

 both distinctions have disappeared ; and while the title of 

 Mving organism is applied to numbers of living things, having 

 no trace of organs in the old sense of the term, and in some, 

 so far as can be now seen, in no other sense, the term organic 

 has long ceased to be applied to substances formed only by 

 living tissues. In other words, substances, once thought to be 

 formed only by living tissues, are still termed organic, al- 

 though they can be now made in the laboratory. The term, 

 indeed, in its old meaning, becomes year by year applicable 

 to fewer substances, as the chemist adds to his conquests over 

 inorganic elements and compounds, and moulds them to more 

 complex forms. 



Although a large number of so-called organic compounds 

 have long ceased to be peculiar in being formed only by living 

 tissues, the terms organic and inorganic are still commonly 

 used to denote distinct classes of chemical substances, and the 

 classification of the matters of which the human body is com- 



