8. E. Moody — Hydrolysis of Salts. 



183 



was made containing 20 grms. to the liter. The standard was 

 found both by determining the zinc precipitated electrolyticaHy 

 and by finding the weight of barium sulphate precipitated by 

 barium chloride. 



In the electrolytic process a portion of 25 cm3 was in each 

 determination drawn from a burette into a beaker of convenient 

 size ; 3 grms. of sodium acetate and l cm3 of acetic acid were 

 added and with a rotating platinum crucible as the cathode a 

 current of one ampere was passed for 30 minutes, when the 

 deposit was washed with water and alcohol, dried and weighed 

 as metallic zinc. 



Results of these experiments are given in the following 

 table : 



Table I. 



Current, 

 amperes. 



1-0 

 1-0 

 1-0 

 1-0 



The entire series gives a mean of 0'1408 grm. of S0 3 equiv- 

 alent to the zinc. 



The content of sulphuric anhydride was found by precipi- 

 tation with barium chloride as barium sulphate, and the results 

 of these experiments are given in the subjoined table : 



Table II. 



Zinc 



sulphate. 



cm 3 . 



Sodium 

 acetic, 

 grms. 



Acetic 

 acid. 

 cm 3 . 



25 



3 



1-0 



25 



3 



ro 



25 



3 



1-0 



25 



3 



1-0 



Time 

 in 



Zinc 



Equivalent 

 of S0 3 



dnutes. 



grms. 



grms. 



30 



0-1153 



0-1413 



30 



0-1146 



0-1405 



30 



0*1149 



0-1408 



30 



0-1147 



0-1406 



Zinc 



sulphate. 



cm 3 . 



BaOI 



cm 3 . 



25 



10 



25 



10 



25 



10 



25 



10 



Mean of 



entire 



series. 



grm. 



y 0-1408 



BaS0 4 Equivalent 



found. of S0 3 



grm. grm. 



0-4109 0-1408 ~) 



04113 0-1410 



0-4101 0-1406 



0-4105 0-14:01 j 



The determinations of zinc and of the barium sulphate gave 

 in the average the same standard for the combined S0 3 . 



Portions of this solution subjected to heat with a mixture 

 of potassium iodide and potassium iodate liberated iodine, and 

 the amounts of iodine found by titration with sodium thio- 

 sulphate are given in the following table : 



Table III. 











Approx. 







Mean of 



Zinc 







Time 



N/10 





Equivalent 



entire 



sulphate. 



KI. 



KIO3. 



in 



Na 2 S 2 0-3. 



I. 



of S0 3 . 



series. 



cm 3 . 



grm. 



cm 3 . 



hours. 



cm 3 . 



grm. 



grm. 



grm. 



25 



1-0 



15 



i 



27*8 



3557 



0-1123 "j 





25 



1-0 



15 



1 

 2" 



28-0 



0-3582 



0-1130 i 

 0-1123 f 



0-1125 



25 



1-0 



15 



3 



27-8 



0-3557 



25 



1-0 



15 



3 



27-8 



0-3557 



0-1123 J 





