384f LIQUID PARTS OF ANIMALS. 



Most persons swallow their spittle once every two minutes. 

 The average weight of the saliva taken into the stomach each 

 time is 6*7 grains. This (in 16 hours) would amount to 3216 

 grains, or 7 ounces. This estimate, (allowing eight hours for 

 sleep, during which little saliva is secreted,) comes very near 

 the estimate of Mitcherlich. 



Haller informs us that 120 Ibs. of saliva were emitted during 

 the treatment of a syphilitic patient : but he does not say how 

 long the treatment continued.* 



Saliva in the mouth varies somewhat in its nature. Most 

 commonly it is very slightly acid, though sometimes it is neutral, 

 and sometimes alkaline. The saliva collected by Mitcherlich 

 from the fistula during meals was acid ; but at other times alka- 

 line. During meals it was secreted so abundantly that it could be 

 collected in drops. At other times the flow was much smaller. 

 Tiedemann and Grmelin assure us that, when pure, saliva is 

 always alkaline ; and the same statement has been made by Dr 

 Donne, f M. Boudet has shown that the saliva and the mucus 

 secreted in the mouth are always alkaline ; but that the secre- 

 tion from the gums is always acid.J 



The specific gravity of saliva varies somewhat, as may be seen 

 from the following table : 



I found it in a case of salivation, . 1*0038 

 Tiedemann and Gmelin found it, . 1-0043 

 Mitcherlich, from . . 1-0061 to 1-0088 



About dinner, Mitcherlich found it, . 1-0074 

 Mean gravity, . . 1-00518 



It has been already observed, that saliva contains white flocks, 

 which gradually subside to the bottom. Mitcherlich found that 

 29-797 of saliva deposited 0-0015 of these white flocks. Accord- 

 ing to this estimate, 100000 parts of saliva contain nearly five 

 parts of white flocks. In another experiment the quantity was 

 greater. Berzelius estimated the quantity much higher, rather 

 more than T G \ ^th of the whole. Part of this difference probably 

 arises from the different temperatures at which the flocks were dried. 

 These white flocks are insoluble in water, alcohol, and acids. 

 They are soluble in potash, and the solution is precipitated by 

 acid. When the flocks are dried they assume a brown colour. 



* Elem. Phys. lib. xviii. f Jour, de Pharm. (3d series,) i. 395. 



$ Ibid. p. 396. 



