Chap. VI.] DIGESTION. 75 



taining a thermometer which indicated a temperature of 38"* to 40 

 Cent. Into each, a quantity of unboiled fibrin was introduced, and 

 the whole allowed to stand for four hours, the temperature being 

 maintained during the whole time, and care being taken that each 

 contained throughout an excess of fibrin. At the end of the period 

 each liquid was filtered. Of the filtrate, which of course contained 

 as much of the fibrin as had been digested during the four hours, 

 10 cub. cent, were measured out and evaporated, and dried at 110" 

 as before. The residues were respectively 



" In the liquid containing hydrochloric acid 0.4079 



" " propionic acid O.OGOl 



" " butyric acid 0.1468 



" " valerianic acid 0.1254 



" Hence, deducting from each of these the above-mentioned resi- 

 due, left when the digestive liquid itself was evaporated, viz. 0.0031, 

 we have, 



" For propionic acid . . . . . . . . 0.0570 



" butyric acid 0.1437 



" valerianic acid . . ' 0.1223 



as compared with 0. 4048 for hydrochloric acid ; these several num- 

 bers expressing the quantities of fibrin by weight digested in 

 presence of equivalent quantities of the respective acids under 

 identical conditions. 



" The results of the experiment may be stated thus: If 100 rep- 

 resent the digestive power of a liquid containing pepsin with the 

 usual proportion of hydrochloric acid, 14.0, 35.4, and 30.2, will repre- 

 sent respectively the digestive powers of the three acids under in- 

 vestigation. 



" 5. In a second experiment in which the procedure was in 

 every respect the same, excepting that all the tubes were plunged 

 into the same water-bath, and the residues dried at 115 C, the 

 results were as follows: 



" Quantity of fibrin dissolved in four hours by 10 cub. cent of 

 the liquid 



"Propionic acid 0.0563 



Butyric acid 0.0835 



Valerianic acid 0.0615 



"The quantity digested by a similar liquid containing hydro- 

 chloric acid was 0.3376. Hence, taking this as 100, the following 

 numbers represent the relative quantities digested by the other 

 acids : 



" Propionic acid . . . . . 16.5 



Butyric acid . . . . . . 24.7 



Valerianic acid 16.1 



