COMPOSITION OF HUMAN SALIVA. 171 



Composition of Human Saliva. 



Water 995-16 



Epithelium 1-62 



Soluble organic matter 1-34 



Sulpho-cyanide of potassium 0-06 



Phosphates of soda, lime, and magnesia 0-98 



Chloride of potassium i 0>g4 

 Chloride of sodium \ ' ' 



1,000-00 



The organic principle of the mixed saliva, called by Ber- 

 zelius ptyaline, is not affected by heat or the acids, but 

 on the addition of an excess of absolute alcohol, is coagu- 

 lated in the form of whitish flakes, which may be readily 

 separated by filtration. This substance has been closely 

 studied by Mialhe, and is described by him under the name 

 of animal diastase. This author regards it as the active 

 principle of the saliva. It is obtained from the human saliva 

 by the following simple process : 



The fluid from the mouth is first filtered, then treated 

 with five or six times its weight of absolute alcohol, by 

 which a white or grayish- white precipitate is formed. This 

 substance is collected on a filter, and is dried in thin layers 

 on a plate of glass in a current of air at from 100 to 120 

 Fahr. It may then be preserved indefinitely in a well- 

 stoppered bottle. 1 The principle thus prepared may be dis- 

 solved in water, when it is insipid, neutral, and becomes read- 

 ily decomposed, giving rise to a substance resembling butyric 

 acid. It has no influence upon the nitrogenized alimentary 

 principles, but when brought in contact with raw or hydrated 

 starch, readily transforms it, first into dextrine, and afterward 

 into glucose. According .to Mialhe, the energy of this action 

 is such that one part is sufficient to effect the transformation 

 of more than two thousand parts of starch. 



The presence of a certain quantity of sulpho-cyanide of 



1 MIALHE, Chimie appliguee d la Physiologic et d la Therapeutiquc, Paris, 1856, 

 p. 43. 



