CHAPTER VI. 

 SALIVA AND SALIVARY DIGESTION. 



I. Conduct of Saliva towards Reagents. 

 II. Detection of Mucin. 



III. Detection of Potassium Sulphocyanate. 



IV. Detection of Ptyalin. 



V. Isolation of the Products of Salivary Digestion. 



I. CONDUCT OF SALIVA TOWARDS REAGENTS. 1 



1. The addition of acetic acid causes a precipitate insolu- 

 ble in an excess of the acid due to the presence of mucin. 



2. Addition of nitric acid: flocculent precipitate, on heat- 

 ing yellow color; on the addition of an excess of caustic soda 

 solution the yellow color becomes more intense or changes to 

 orange. The reaction is due to mucin (and albumin?}. 



3. Shake a little saliva with an equal volume of water and 

 some Millon's reagent: white precipitate, which gradually 

 turns red on boiling (mucin). 



4. Add caustic soda solution and then a very small quan- 

 tity of a dilute copper sulphate solution: violet color in con- 

 sequence of the presence of mucin. 



II. DETECTION OF MUCIN. 



Twenty cubic centimeters of saliva are poured into 100 cc. 

 of absolute alcohol and thoroughly stirred. The white floc- 

 culent precipitate is filtered off, washed with alcohol, then 



1 Use small quantities for the tests. 



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