8 CHEMICAL COMPOSITION OF HUMAN BODY. 



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 or- 

 ganized or living beings, animal or vegetable; these 

 being called organized, inasmuch as they are charac- 

 terized by the possession of different parts called organs. 

 But with advancing knowledge, both distinctions have dis- 

 appeared ; and while the title of living 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, 

 although 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 com- 

 pounds 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 composed into the organic and the 

 inorganic is convenient, and will be here employed. 



No very accurate line of separation can be drawn 

 between organic and inorganic substances, but there are 

 certain peculiarities belonging to the former which may 

 be here briefly noted. 



I . Organic compounds are composed of a larger number 

 of Elements than are present in the more common kinds of 

 inorganic matter. Thus, albumen, fibrin, and gelatin, the 



