146 



Phelps and Weed — Succinic Acid. 



the characteristic color of free iodine disappeared, or by add- 

 ing portions of a dilute sodium thiosnlphate solution until the 

 blue color of the starch solution introduced was bleached. In 

 all of the experiments in this table, also, five cubic centimeters 

 of a potato starch solution were added before the titration 

 was begun. 



Table I. 







HC1 value of 









HC1 



Na 2 S 2 3 



Iodine 









solution 



solution 



solution 



HC1 



Error in 





used 



used 



used 



found 



HC1 



No. 



grm. 



grm. 



grm. 



grm. 



grm. 



( 1) 



0-1074 



0-1075 







0-1075 



0-0001 + 



( 2) 



0-1074 



0-1074 







0-1074 



o-oooo ± 



( 3) 



0-1074 



0-1075 







0-1075 



0-0001 + 



( 4) 



0-0520 



0-0520 







00520 



o-oooo± 



( 5) 



0-1560 



0-1562 







01562 



0-0002 + 



( 6) 



0-0645 



0-0712 



0-0068 



0-0644 



o-oooi — 



( *) 



0-0968 



0-1068 



o-oioi 



0-0967 



o-oooi — 



( 8) 



0-0645 



0-0712 



0-0067 



0-0645 



0-0000 + 



( 9) 



0-0968 



0-1068 



0*0101 



0-0967 



o-oooi — 



(10) 



0-0484 



0-0534 



0-0050 



0-0484 



0-0000 + 



(11) 



0-0645 



0-0748. 



0-0104 



0-0644 



o-oooi — 



(12) 



0-0484 



0-0534 



0-0050 



0-0484 



0-0000 + 



(13) 



0-0645 



0-0712 



0-0066 



0-0646 



0-0001 + 



In experiments (1) to (5) inclusive of Table I the excess of 

 the sodium thiosulphate was determined by the addition of 

 decinormal hydrochloric acid to color with starch, while in 

 the other experiments the excess was determined similarly by 

 titration against the decinormal iodine solution. In experi- 

 ments (1) to (7) inclusive, the iodine set free on the addition 

 of the potassium iodate to the potassium iodide was removed 

 by boiling as described above. In experiments (8) to (13) 

 inclusive of the same table, the iodine set free was removed 

 by dilute sodium thiosulphate, which was added until the color 

 of the starch solution present was bleached. 



The solution of hydrochloric acid used to set free the iodine 

 was standardized as silver chloride as well as against a deci- 

 normal sodium hydroxide solution, the exact strength of which 

 was established by titrating with the organic substances as 

 standards, as Ave have shown in a former paper.* It was shown 

 also in that paper that the standards obtained by silver chloride 

 and the organic substances are in agreement within the limits of 

 experimental error. From an inspection of Table I, in which 

 the action of a decinormal solution of hydrochloric acid, stand- 



* This Journal, xxvi, 138. 



