354 CHEM1STR Y OF THE DIGESTIVE PROCESSES. 



2. Laborde l compared the inverting power of gastric juice on cane-sugar 

 with that of a solution of pure hydrochloric acid in water, of equal acidity to 

 the gastric juice, and under similar conditions. He found that the hydro- 

 chloric acid inverted much more rapidly than the gastric juice, which 

 possessed much the same inverting power as a solution of lactic acid of equal 

 concentration. He also found that gastric juice converted starch into grape- 

 sugar and dextrin much more slowly than a solution of hydrochloric acid 

 under similar conditions. On the other hand, Szabo 2 found that peptones do 

 indeed interfere with the action of dilute hydrochloric acid on starch ; but, 

 contrary to Laborde, found that the action of gastric juice on starch lies in 

 intensity much closer to that of hydrochloric than to that of lactic acid. 



3. In treating of the digestive enzymes, it has been seen that these are 

 much less injured by hydrochloric acid, in presence of albumoses and peptones, 

 than by free hydrochloric acid alone, which shows that hydrochloric acid in 

 presence of albumoses and peptones berfkves as if it entered into combina- 

 tion with them. 



4. Berthelot and Jungfleisch 3 showed that, when a substance which is 

 soluble in each of two solvents, which are not completely soluble in each 

 other, is shaken up with a quantity of both solvents, it divides itself between 

 the two solvents so that the ratio of its concentrations in each is constant, and 

 does not vary with the proportion of the two solvents used, nor the amount of 

 soluble material used. This constant ratio they called the coefficient de 

 partage, which may be rendered in English "coefficient of distribution." 4 

 For example, if succinic acid be well shaken up with water and ether, the 

 concentration of succinic acid in the watery layer will always be about six 

 times as great as in the ethereal layer, no matter, within wide limits, 5 what 

 have been the quantities of ether, water, and succinic acid used; the co- 

 efficient of distribution is here six. Mineral acids are much more soluble in 

 water compared with ether than are organic acids ; accordingly the co- 

 efficients of distribution of the mineral acids for these two solvents are 

 much larger than those of the organic acids. 



Richet 6 made use of this property to test whether pure gastric juice con- 

 tains only hydrochloric acid, or hydrochloric acid plus organic acids. He 

 found that the coefficient of distribution was 137*1. To a portion of the 

 same gastric juice he next added barium lactate, and found that the co- 

 efficient was reduced to 9*9, that of lactic acid is 8*8 to ll'O. This experiment 

 shows that the acid first present was a mineral acid, which afterwards dis- 

 placed nearly all the lactic acid from combination, so that in the second case 

 the acidity was mainly due to lactic acid. Richet further added sodium 

 acetate (a) to a solution of hydrochloric acid in water ; (b) to gastric juice of 

 equal acidity, and found that in the first case the coefficient was reduced to 

 1*7 (practically that of acetic acid, 1*4), while in the second case the co- 

 efficient was only reduced to 5 to 5 '8. Richet supposes that this difference is 

 due to the hydrochloric acid in the gastric juice being combined feebly with 

 some other substance.- When sodium acetate is added to hydrochloric acid 

 alone, the base will be shared between the two acids in proportion to their 

 mutual avidities for it, which are in the ratio of 1 to '03. That is to say, about 



1 Gaz. med. de Paris, 1874, Nos. 32-34, pp. 399, 411, 422. 



2 Ztsclir. f. pliysiol. Chem., Strassburg, 1877, Bd. i. S. 140. 



3 Ann. de chim., Paris, 1872, Ser. 4, tome xxvi. p. 396. For a complete account of 

 this subject, see Ostwald, " Lelirbucli der allgemeinen Cliem.," Leipzig, 1891, Aufi. 2, 

 Bd. i. S. 809. 



4 This term has been proposed by Gamgee, "Physiological Chemistry," vol. ii. p. 97, 

 as well as "coefficient of repartition. " 



5 The quantities of solvent must be so chosen, compared with the quantity of soluble 

 substance, that the solutions are not too concentrated. 



6 "Le sue gastriqne chez 1'homme et les animaux, ses proprietes chemiques et physio- 

 logiques," Paris, 1878, p. 37. 



