PROXIMATE CONSTITUENTS. 517 



But in addition to the power of oxygen, hy- 

 drogen, carbon, and nitrogen, to form ternary 

 and quaternary compounds, it is worthy of special 

 notice, that many more atoms of the same ele- 

 ments unite together in forming organic combi- 

 nations than are found in those of inorganic 

 bodies. For example, water is composed of one 

 atom of oxygen to one of hydrogen ; carbonic 

 acid, of carbon one atom to two of oxygen ; and 

 so of innumerable other binary compounds ; 

 whereas the acid, saccharine, oily, and resinous 

 constituents of plants, are generated by the imme- 

 diate union of many oxygen, hydrogen, and car- 

 bon atoms. Starch is composed of seven atoms 

 carbon, six of oxygen, and six of hydrogen ; 

 sugar of twelve atoms of carbon, eleven of 

 oxygen, and eleven of hydrogen ; while the oil 

 of peppermint consists of carbon atoms ten, hy- 

 drogen ten, and oxygen one. The resins and 

 fixed oils contain still higher numbers of the 

 same atoms, as may be seen by referring to 

 p. 146 of the First Book, where it has been shewn 

 that this constitutes the principal difference 

 between the volatile and more tenacious com- 

 pounds of organic matter. From which it is 

 probable that the quaternary unions of oxygen, 

 hydrogen, carbon, and nitrogen, to form the 

 proximate constituents of the blood and solid 

 tissues of animals, contain still higher num- 

 bers of atoms of the same elements. So that 



