Jamieson — Polythionic Acids. 



641 



In the table of analyses given below, the actual amount of 

 Na 2 S,0 6 present for each titration is stated. The first six 

 titrations were made with the potassium iodate solution men- 

 tioned above, which contained 3*567 g. of KI0 3 in 1000 cc , and 

 according to the equation of the reaction 



2Na 2 S 4 6 + 



KIO a + 10HCl = 4H SO 

 7IC1 + 3KC1 



2Xa SO. + 2K .SO, + 



the equivalent of the solution is l cc = 001287 g. of Na 2 S 4 6 . The 

 sodium tetrathionate was titrated in the same manner as the 

 thiosulphate except that it was not necessary to take precau- 

 tions about cooling the hydrochloric acid before adding the 

 tetrathionate. 



The following results were obtained : 





Wt. of Na 2 S 4 6 



ccKI0 3 



Wt. of Na 2 S 4 6 





No. 



taken 



used 



found 



Error 



1 



•0452 



35-1 



•0452 



•oooo 



2 



•0340 



26*35 



•0339 



— '0001 



3 



•0429 



32-2 



•0427 



— '0002 



4 



•0612 



47-5 



•06 1 1 



— -oooi 



5 



•0400 



30-7 



•0395 



— '0005 



6 



•0672 



52-0 



•0669 



— -0003 



n 



•0454 



13-85 



•0457 



+ '0003 



8 



•0507 



15°3 



•0505 



— '0002 



9 



•0640 



19-35 



•063S 



— -0002 



10 



•0766 



23'2 



•0765 



— -oooi 



11 



•1373 



41-7 



•1375 



+ '0002 



12 



•0872 



26-43 



•0871 



— -oooi 



13 



•1065 



32-3 



•1065 



•0000 



14 



•0890 



26-8 



•0884 



— -0006 



f Titrations 7-14 were made with an iodate solution which had the value 

 . 1" - -003297 g. of Na 2 S 4 6 . 



These results show a satisfactory agreement with the actual 

 amounts of sodium tetrathionate taken. 



Dithionates were found to react so slowly with potassium 

 iodate in the presence of strong hydrochloric acid that it was 

 possible to titrate and determine the amount of sodium thio- 

 sulphate in the presence of large quantities of potassium 

 dithionate. Likewise, tetrathionates could be estimated in the 

 presence of dithionates. The stability of dithionates has been 

 observed previously by R. H. Ashley.* It was found that 

 barium and sodium dithionate were only partially decomposed 

 by potassium iodate after reacting for a day and no iodine was 



* This Journal, xxii, 259. 



