388 LIQUID PARTS OF ANIMALS. 



Tiedemann and Gmelin made a great many experiments on 

 human saliva, and on the saliva of the dog and the sheep.* They 

 found the specific gravity of saliva made to flow by the stimulus 

 of tobacco smoke to be 1-0043 at 53^. It reacted feebly as an 

 alkali, and never was acid. The residue when evaporated to 

 dryness amounted to 1-19 or 1-14 per cent. This residue being 

 incinerated, left 0-25 of ashes, of which 0-203 were soluble, and 

 0-047 insoluble in water consisting of earthy phosphates. 



100 parts of the residue obtained by evaporating saliva to dry- 

 ness being analyzed, yielded the following products : 



1. Fatty matter, analogous to cerebrote, substances soluble in al- 

 cohol and water, extract of meat, chloride of potassium, lactate 

 of potash, sulphocyanate of potash, . . 31-25 



2. Animal substance precipitated by cooling from the so- 

 lution of boiling alcohol with sulphate of potash and 

 some chloride of potassium, . . 1*25 



3. Matters soluble in water only, viz. salivin, much phos- 

 phate, and a little of sulphate of an alkali, and chloride 



of potassium, . . . 20-00 



4. Substances neither soluble in water nor alcohol, viz. 

 mucus, a little albumen, with alkaline carbonate and 

 phosphate, _,>.,., . 40-00 



92-5 



The 8-5 per cent, deficient was probably owing to the residue of 

 soda still retaining water. 



It may be worth while to notice the differences in the charac- 

 ters of salivin, as stated by Berzelius and Tiedemann and Gmelin. 

 Berzelius found it white, Tiedemann and Gmelin light yellowish- 

 brown. 



Berzelius states it as soluble in water; Tiedemann and Gmelin 

 found that every time it was dissolved in water it left alight-brown 

 membranous residue. 



According to Berzelius, it is not precipitated by infusion of 

 nut-galls, diacetate of lead, nor corrosive sublimate. According 

 to Tiedemann and Gmelin, it is precipitated not only by infusion 

 of nut-galls, but also by lime-water, solutions of alum, and by 

 neutral salts of copper, lead, and iron. 



It is pretty clear that the salivin of Tiedemann and Gmelin 

 was mixed with the mucus of the saliva. 



* Tiedemann and Gmelin sur la Digestion, i. 4. 



