304 Gooch and Bosworth — lodometric Estimation of Silver. 



the silver present. In Table III are given the details of exper- 

 iments made in this manner. 









Table IN. 







Silvei 



• taken. 













Volume 













Error in 



of solu- 





HN0 3 



K 2 Cr0 4 



Na a S a O» 



Silver 



terms of 



tion 



"Weight 



present 



weight 



used 



found 



silver 



cm 3 . 



grm. 



grm. 



grm. 



cm 3 . 



grm. 



grm. 



25 



0-1348 



0-063 



0-60 



18*35 



0-1342 



— 0-0006 



20 



0-1078 



0-063 



0-65 



14-67 



0-1073 



— 0-0005 



15 



0-0808 



0*063 



0*65 



11-06 



0-0809 



+ 0-0001 



15 



0-0808 



0-063 



0-65 



10-96 



0-0802 



-0-0006 



20 



0-1078 



0-063 



0-65 



14-67 



0-1073 



— 0-0005 



30 



0-1618 



0-063 



0-75 



22-02 



0-1610 



— 0-0008 



20 



0-1078 



0063 



0-65 



14-71 



0-1075 



— 0-0003 



25 



0-1348 



0-063 



0-65 



18-41 



0-1347 



— 0-0001 



25 



0-1348 



0-063 



0-65 



18-41 



0-1347 



— 0-0001 



20 



0-1078 



0-063 



0-65 



14-74 



0-1078 



o-oooo 



The results obtained justify the conclusion that silver can be 

 accurately estimated by precipitating as silver chr ornate with 

 the use of a sufficient excess of potassium chromate, dissolving 

 the precipitate formed in ammonia, reprecipitating by boiling 

 to low volume, and determining iodometrically either the chro- 

 mate ion in combination with the silver or the chromate ion 

 of the potassium chromate remaining after precipitation of 

 the silver with a known amount of standard potassium 

 chromate. 



