INORGANIC ALIMENTARY PRINCIPLES. 63 



and in rice, O8 per cent. 1 The above is the proportion in 

 the grains after desiccation. 



Fat, both animal and vegetable, may be either liquid or 

 solid. It has a peculiar oily feel, a neutral reaction, is in- 

 soluble in water and soluble in alcohol (particularly hot alco- 

 hol), chloroform, ether, benzine, and solutions of soaps. The 

 solid varieties are exceedingly soluble in the oils. Treated 

 with alkalies, at a high temperature and in the presence of 

 water, they are decomposed into fatty acids and glycerine, 

 the acid uniting with the base to form a soap. Alkaline, 

 mucilaginous, and some animal fluids (particularly the pan- 

 creatic juice) are capable of holding fat in a state of minute 

 'and permanent subdivision and suspension, forming what are 

 known as emulsions. 



The composition of many of the fats and oils has never 

 been definitely ascertained, on account of the difficulty in 

 obtaining them in a state of absolute purity. They contain 

 carbon, hydrogen, and oxygen, but the latter elements do 

 not exist in the proportions to form water. The composition 

 of stearine is C 71 H 70 O 8 . 



As alimentary principles, fats and oils are undoubtedly 

 of great importance. They are supposed by many to be 

 particularly concerned in the function of calorification. It 

 has been proven by repeated experiments that fat, as a single 

 article of diet, is insufficient for the purposes of nutrition. 



Inorganic Alimentary Principles. Physiological chem- 

 istry has shown that all the organs, tissues, and fluids of the 

 body contain inorganic matter in greater or less abundance. 

 The same is true of vegetable products. All the organic 

 nitrogenized principles contain mineral substances which 

 cannot be removed without incineration, and which must be 

 considered as actually part of their substance. When new 

 organic matter is appropriated by the tissues to supply the 



1 PATEN, Precis TJieorique et Pratique des Substances Alimentaires, Paris, 1865, 

 p. 265. 



