of Acids by Carbohydrates. 



Experiment III. 



Weight of each carbohydrate, 0*25 gm. 



Time of experiment, 18 hours. 



Mean temperature, 14° C. 



Volume of standard solution added to each, 18'2 c.c. 



Volume of solvent (CCI4), 11*8 c.c. 



1 c.c. of standard solution contained O'OOSOl gra. 



Weight of hydrogen chloride added, 009 12 gm. 



551 



Experiments were now made in order to discover the relation- 

 ship existing between the amount of acid adsorbed by the solid 

 and the amount of acid remaining in solution. 



For this purpose, one gram of starch was placed in each of 

 seven tightly stoppered vessels, 10 c.c. of dry carbon tetrachloride 

 were added to each, and the mixture was allowed to stand for 

 about one hour, so that the starch might become fully saturated 

 with solvent: various quantities of a solution of hydrogen chloride 

 in the same solvent were added to each respectively, and the volume 

 was made up to 100 c.c. with dry solvent. 



After remaining at the ordinary temperature for eighteen 

 hours, 25 c.c. of the clear liquid were withdrawn, shaken about with 

 much water and the whole was titrated against baryta of known 

 strength. 



From these results, the amount of acid adsorbed by the starch, 

 and hence the amount left in solution, was determined. 



The results are given in detail below. 



For purposes of calculation the well-known exponential for- 

 mula has been used, namely 



^ — hnn 



— /t(/2 J 



a 



where n and k are constants. 



