388 Hale — Initiative Action of Iodine and other 



Table VII. 



No extra dilution. Volume about 110 cra3 . 

 to/10 

 As 2 O s . to/1 01 sol. KHC0 3 . Starch sol. Color. 



cm 3 . 

 1 ordinary pure potato pale blue 



deep- blue 

 " ordinary pure rice blue, slightly 



purplish 

 " ordinary pure soluble blue, slightly 



purplish 

 " ordinary pure arrow- 

 root deep blue 

 " KI pure starch good blue 

 " yellow 



It is at once seen that these values are coincident within a 

 drop and that all the starch solutions are within the limits set 

 by a plain iodine reading on the one hand and a potassium 

 iodide starch reading on the other, though there was no dilu- 

 tion of the standard solutions. 



To test the action of pure starch further some titrations 

 were made with pure potato starch in varying amounts, and 

 again with increasing amounts of acid potassium carbonate. 

 As the loss of iodine, previously noticed, had been almost 

 complete when 10 cm3 of arsenite solution had been titrated, 

 this quantity was used. Again there was no dilution. 



cm 3 . 



cm 3 . 



cm 3 . 



50 



j 49-11 



5 



(.49-13 





u 



49-13 



a 



a 



49-14 



a 



a 



49-15 



u 



u 



49-15 



. u 



u 



49-13 



a 











Table 



VIII. 

















Nc 



» extra 



dilution. 









to/10 





















A.S2O3. 



w/10 I sol. 



KilCO- 



). Starch sol. 











Color. 



cm 3 . 



cm 3 . 



cm 3 . 



cm 3 . 















10 



9-82 



5 



1-5 



ordinary 



pur 



e potato 



deep blue, 





















purplish 



u 



9-82 



u 



5 





u 





u 





deep blue 



a 



j 9-82 

 ( 9-84 



u 



10 





u 





a 



pale 



blue, purplish 

 deep blue 



a 



9-82 



a 



15 





a 





a 





deep blue 



u 



9-84 



u 



20 





u 





a 





deep blue 



u 



9-85 



a 



25 





a 





a 





deep blue 



50 



49-15 



a 



25 





u 





a 





medium blue 



a 



49-35 



a 



25 



ordi 



nary 



imr 



>ure 





abundant red 



The last experiment was made to see if the conditions were 

 the same as in the preceding experiments save for the starch, 

 and a loss of 0'20 cm3 of iodine solution seems to prove that 

 there were similar conditions. There appears to be no loss 

 with any amount of pure starch solution, even when 50 cm3 of 



