390 



LIQUID PARTS OF ANIMALS. 



4. Matters insoluble in water and alcohol, viz. mucus or 

 coagulated albumen, a little phosphate and carbonate of 

 lime. . . . .0*05 



99-88 



It would appear from an observation of Leuchs that, when starch 

 is boiled with saliva, the solution becomes more liquid, and ac- 

 quires a sweet taste.* From this it would seem that saliva is ca- 

 pable of converting starch into sugar. He found that neither 

 albumen, gelatin, nor salivin possessed this property. 



The saliva is sometimes liable to undergo morbid alterations. 

 There are two cases on record in which it contained a good deal 

 of oxalic acid. Clerc mentions that he has sometimes observed 

 the saliva in diseased persons acid and sometimes alkaline; 

 but he does not seem to have made any observations to deter- 

 mine the nature of the acid or alkali present. It varies much 

 in quantity and consistence : but no accurate set of observations 

 has yet been made upon the alterations induced in saliva during 

 various diseases. According to Dr Donne, the saliva becomes 

 acid when inflammatory diseases of the stomach exist, and it as- 

 sumes its natural state of alkalinity as soon as that inflammatory 

 affection ceases.f 



Depositions from the saliva are frequently observed on the 

 teeth. Such depositions are known by the name of tartar. It 

 is a yellowish white bony-looking concretion, which gradually 

 accumulates on the teeth unless they be regularly cleaned. At 

 first it is little else than the mucus of the salivary ducts, which 

 gradually adheres to the teeth and becomes discoloured. But 

 by degrees subsesquiphosphate of lime appears, augments the 

 deposit, and renders it harder. 



Tartar, according to the analysis of Berzelius,| is compos- 

 ed of, 



Earthy phosphates, . t 79*0 



Mucus, . . >V 125 



Salivin, . . *. 1-0 



Animal matter soluble in muriatic acid, 7-5 



100-0 



* Poggendorf s Annalen. xxii. 623. 

 f Ann. de Chim. et de Phys. Ivii. 414. 

 | Annals of Philosophy, ii. 381. 



