ADIPOCERE. 



99 



THE FATS. 



The chemical elements entering into the composition of the 

 fats are carbon, hydrogen, and oxygen. The fats are widely dis- 

 tributed throughout the human body. The percentage in the solids 

 and fluids is as follows : 



Sweat 0.001 



Vitreous humor 0.002 



Saliva 0.02 



Lymph 0.05 



Synovia 0.06 



Liquor amnii 0.06 



Chyle 0.2 



Mucus 0.3 



Blood 0.4 



Bile 1.4 



Milk . .4.3 



Cartilage 1.3 



Bone 1.4 



Crystalline lens 2.0 



Liver 2.4 



Muscles 3.3 



Hair 4.2 



Brain 8.0 



Nerves 22.1 



Adipose tissue "... 82. 7 



Marrow . 96.0 



Fats are regarded by chemists as composed of fatty acids and 

 glycerin, and are called glycerids or glyceric ethers. When 

 treated with superheated steam and mineral acids, and in the 

 human body under the influence of steapsin, the lipolytic enzyme 

 of the pancreatic juice, the fats are decomposed into glycerin and 

 the respective fatty acid. This change is expressed by the follow- 

 ing formula, palmitin being taken as an example : 



C 3 H 5 (O.C 15 H 31 CO) 3 



Palmitin. 



3H 2 --= C 3 H 5 (OH) 3 



Water. Glycerin. 



3C 15 H 31 CO.OH 



Palmitic acid. 



There are three varieties of fats : Olein, C 3 H 5 (OC 17 H 33 CO) 3 ; 

 palmitin, C 3 H 5 (OC 15 H 31 CO) 3 ; and stearin, CgH^OC^H^CO),. 

 These differ in several particulars, one of the most important 

 being their melting-points : Olein melts at 5 C. ; palmitin, at 

 45 <C. ; and stearin, at from 53 to 66 C. Their respective acids 

 are oleic, palmitic, and stearic. 



Fats are characterized by being insoluble in water, slightly 

 soluble in alcohol, and very soluble in ether and chloroform. All 

 fats are mixtures of the three varieties, the difference in the con- 

 sistency of any given fat depending upon the proportion in which 

 the neutral fats are present. Thus in the more solid fats, such 

 as suet, stearin predominates, while in the fluid fats it is olein 

 which is in excess. The latter exists in human fat to the amount 

 of from 67 to 80 per cent. When fats decompose or become 

 " rancid," propionic, acetic, and formic acids are produced. 



Adipocere. It sometimes happens that when bodies are dis- 

 interred, instead of being found in a condition of putrefaction, 

 they are discovered to have been changed into adipocere or grave- 

 wax. This is a peculiar substance of a waxy nature, and consists 

 of calcium soaps, of which the fatty acids are palmitic and stearic. 

 Acid ammonium soap has been found in some cases. This change 



