Chap. VI. DIGESTION. 91 



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

 of the liquid : 



" Hydrochloric acid .. .. 0-2915 



Propionic acid 0*1490 



Butyric acid 01044 



Valerianic acid .. .. .. 0*0520 



" Comparing, as before, the three last numbers with the first 

 taken as 100, the digestive power of propionic acid is repre- 

 sented by 16*8; that of butyi'ic acid by 35-8; and that of 

 valerianic by 17-8. 



" The mean of these three sets of observations (hydrochloric 

 acid being taken as 100) gives for 



" Propionic acid 158 



Butyric acid 32-0 



Valerianic acid 21-4 



" 7. A further experiment was made to ascertain whether tho 

 digestive activity of butyric acid (which was selected as being 

 apparently the most eflBcacious) was relatively greater at ordinary 

 temperatures than at the temperature of the body. It was 

 found that whereas 10 cub. cent, of a liquid containing the ordi- 

 nary proportion of hydrochloric acid digested 0*1311 gramme, 

 a similar liquid prepared with butyric acid digested 0*0455 

 gramme of fibrin. 



" Hence, taking the quantities digested with hydrochloric acid 

 at the temperature of the body as 100, we have the digestive 

 power of hydrochloric acid at the temperature of 16° to 18° 

 Cent, represented by 44*9; that of butyric acid at the same 

 temperature being 15*6." 



We here see that at the lower of these two temperatures, 

 hydrochloric acid with pepsin digests, within the same time, 

 rather less than half the quantity of fibrin compared with 

 what it digests at the higher temperature; and the power of 

 butyric acid is reduced in the same proportion under similar 

 conditions and temperatures. We have also seen that butyric 

 acid, which is much more eflBcacious than propionic or vale- 

 rianic acids, digests with pepsin at the higher temperature less 

 than a third of the fibrin which is digested at the same tempera- 

 ture by hydrochloric acid. 



