ITS CHEMICAL CONSTITUENTS. 19 



In the saliva of the dog Jacubowitsch found l'037f, and in that of 

 the horse Magendie and Rayer found about 1-g- of solid residue. 



In 100 parts of the solid constituents of mixed human saliva, 

 Tiedemann andGmelin found 21'3-g- of fixed salts, while L'Heritier 

 found only 6*8$, and Jacubowitsch, on the other hand, 3 7 -5-g-; the last- 

 named observer found that the mineral constituents predominated 

 very much in the saliva of the dog, where they amounted to 65*5^ 

 of the solid residue ; in the horse, according to Magendie, they 

 amounted to 40-g-. 



In relation to the individual mineral constituents of the saliva, 

 we are as little able to arrive at any definite conclusion regarding 

 those which exist preformed in it from the analyses of the ash of 

 the salivary residue, as in the case of most of the other animal juices. 

 We have, however, already remarked, that a great part of the alkali 

 in the saliva is combined with ptyalin, from which it is separated 

 by the weakest acids, as, for instance, carbonic acid. From the 

 quantities of acids which are requisite for the saturation of alkaline 

 saliva, Wright has concluded that in the normal state the alkali 

 never amounts to 1-J- of the saliva. In the ash of the salivary resi- 

 due the alkali is for the most part combined with phosphoric acid; 

 thus Enderlin* found 23'122-J of the tribasic, and Jacubowitsch 

 51'1-g- of the bibasic phosphate of soda in the ash 



We never find more than a trace, and often not that, of the 

 alkaline sulphates in fresh saliva ; and even in the ash they are 

 not found in any considerable quantity ; hence, as in the case of 

 the phosphoric acid, the sulphuric acid must have been formed 

 from other compounds during incineration. 



In the ash of human saliva Enderlin found 21 '35-g- of sulphate 

 of soda ; and in that of horses 5 saliva I found 1 *604f of this salt. 



In Wright's method of determining the sulphocyanide of 

 potassium, which consists in dissolving in water the extract taken 

 up by ether, and precipitating with basic acetate of lead, not 

 only sulphocyanide of lead, but a far larger quantity of a com- 

 pound of lead with a fatty acid, is thrown down; from this circum- 

 stance Wright's determinations are on an average ten times too 

 high. 



The chlorides of potassium and sodium especially preponde- 

 rate over the other mineral constituents of the saliva. 



Enderlin found 61*930 of alkaline chlorides in the ash of the 

 saliva, and Jacubowitsch 46'2-g- ; in the dog they amounted, ac- 

 cording to the last-named observer, to 85'7-g-. 



* Ann. d. Ch. und Pharm. Bd. 49, S. 317- 



c 2 



