230 Gooch and Kobayashi — Determination of Thorium. 







A. {Continued). 







Precipitation in hot solution. 





ThO s 



Th0 2 found 



Th0 2 found 



Error in 



Error in 



taken as 



in treatment 



in treatment 



treatment of 



treatment of 



nitrate 



of precipitate 



of filtrate 



precipitate 



filtrate 



grm. 



grm. 



grm. 



grm. 



grm. 



01290 



01291 



0-1290 



+0-0001 



0-0000 



01506 



0-1505 



01504 



—00001 



—00002 



0-1722 



01723 



0-1720 



+00001 



—00002 



01937 



01944 



01937 



+0-0007 



o-pooo 



0-2151 



0-2153 



0-2151 



+00002 



00000 





B. 



Precipitation in cold solution. 





00238 



00236 



0-0236 



—00002 



—00002 



00474 



00475 



0-0472 



+0-0001 



—00002 



00711 



00707 



0-0709 



—0-0004 



—0-0002 



00711 



00710 



00711 



—0-0001 



00000 



00947 



00946 



0-0945 



—00001 



—00002 



01183 



01180 



01184 



—00003 



+00001 



01419 



01417 



01416 



—0-0002 



—00003 



01658 



01654 



01658 



—00004 



00000 



0-1895 



0-1888 



0-1890 



—0-0007 



—00005 



0-2130 



0-2128 



0-2133 



—0-0002 



+0-0003 



0-2366 



0-2365 



0-2368 



—00001 



+00002 



The work described shows that thorium may be esti- 

 mated by an oxidimetric titration based upon the pre- 

 cipitation of thorium oxalate, provided that the precau- 

 tion is taken to add the thorium salt gradually during 

 the process of precipitation to an excess of oxalic acid. 

 In the reverse procedure the tendency of thorium oxalate 

 to fall as a basic salt is manifest and this tendency is 

 especially marked in hot solutions. An accurate deter- 

 mination may be made either by the direct oxidation of 

 the precipitated thorium salt, Th(C 2 4 ) 2 , or by determin- 

 ing the excess remaining in solution from a known 

 amount of oxalic acid, after filtering and washing the 

 precipitate. 



