CHEMICAL PHYSIOLOGY. 6 



the secretory nerves. Its composition is not yet 

 ascertained. 



The mixture of sublingual and submaxillary saliva 

 in man (not in animals) contains rhodanate or sulpho- 

 cyanate (also termed rhodanide or sulphocyanide) of 

 potassium and sodium C N K S, and C N Na S, recog- 

 nised by the red colour which iron-chloride imparts to 

 saliva, or to the distillate obtained from it with acids. 

 This phenomenon admits at present of no particular 

 theory. 



The saliva which is secreted by the parotid glands can 

 easily be collected by the introduction of canulae into 

 the ducts. It is an alkaline, hardly viscous fluid, which 

 contains a little albumen, some globuline, a particular 

 ferment termed ptyaline, but no mucine. It contains 

 much rhodanate, and is the most suitable material for 

 preparing the distillate of rhodanic acid. It contains, 

 water 995*3; solids 4*7; of these are organic 1*4; 

 mineral 3*3 ; of the latter there is lime carbonate 1/2. 

 The parotid saliva transforms starch into sugar by 

 means of the ferment termed ptyaline. This is the 

 only agent in saliva which has that power. It can be 

 isolated by adding phosphoric acid and subsequently 

 lime to saliva. Ptyaline adheres to the phosphate, is 

 washed out by water, and precipitated by alcohol. It 

 contains nitrogen but is not albuminous, refusing to 

 yield the xanthoproteic acid reaction with nitric acid. 

 The diastase of malt has a similar action used in trade 

 fermentations. An interesting and important applica- 

 tion has lately been made of diastase by Baron Liebig, 

 for the production of a food for infants, which supplies 



