20 CHEMICAL COMPOSITION OF HUMAN BODY. 



pounds, is, in those which are most abundant in the highly 

 organized tissues of animals, augmented, 1st, by their contain- 

 ing nitrogen, which, among all the elements, may be called the 

 least decided in its affinities, and that which maintains with 

 least tenacity its combinations with other elements; and 2dly, 

 by the quantity of water which, in their natural state, is com- 

 bined with them, and the presence of which furnishes a most 

 favorable condition for the decomposition of nitrogenous com- 

 pounds. Such, indeed, is the instability of animal compounds, 

 arising from these several peculiarities in their constitution, 

 that, in dead and moist animal matter, no more is requisite 

 for the occurrence of decomposition than the presence of at- 

 mospheric air and a moderate temperature ; conditions so com- 

 monly present, that the decomposition of dead animal bodies 

 appears to be, and is generally called, spontaneous. The modes 

 of such decomposition vary according to the nature of the origi- 

 nal compound, the temperature, the access of oxygen, the pres- 

 ence of microscopic organisms, and other circumstances, and 

 constitute the several processes of decay and putrefaction ; in 

 the results of which processes the only general rule seems to 

 be, that the several elements of the original compound finally 

 unite to form those substances, whose composition is, under 

 the circumstances, most stable. 



The organic compounds existing in the human body may 

 be arranged in two classes, namely, the azotized, or nitrogenous, 

 and the non-azotized, or non-nitrogenous principles. 



The non-azotized principles include the several fatty, oily, 

 or oleaginous substances, as olein, stearin, cholesterin, and 

 others. In the same category of non-nitrogenous substances 

 may be included lactic and formic acids, animal glucose, sugar 

 of milk, &c. 



The oily or fatty matter which, inclosed in minute cells, 

 forms the essential part of the adipose or fatty tissue of the 

 human body (p. 40), and which is mingled in minute particles 

 in many other tissues and fluids, consists of a mixture of stearin, 

 palmitin, and olein. The mixture forms a clear yellow oil, of 

 which different specimens congeal at from 45 to 35. 



Cholesterin, a fatty matter which melts at 293 F., and is, 

 therefore, always solid at the natural temperature of the body, 

 may be obtained in small quantity from blood, bile, and ner- 

 vous matter. It occurs abundantly in many biliary calculi ; 

 the pure white crystalline specimens of these concretions being 

 formed of it almost exclusively. Minute rhomboidal scale- 

 like crystals of it are also often found in morbid secretions, as 

 in cysts, the puriform matter of softening and ulcerating 

 tumors, &c. It is soluble in ether and boiling alcohol ; but 



