374 Gooch and Kobayashi — Determination of Fluorine 



aids greatly in the filtration and washing if only a volu- 

 metric determination is to be made, but this device can 

 not be applied when the gravimetric determination of the 

 ignited thorium oxide is desired. 



In Table II are recorded the details of experiments 

 made according to the procedure outlined. 







Table II. 











Gravimeti 



ic and Volumetric Determinations of Fluorine 









Precipitated as Thorium Fluoride. 





i 













Total 







Fluorine found: 



Error 



volume 



Acidity 



Fluorine Gravimet- Volumet- 



Gravimet- 



Volumet- 



of 



of acetic 



taken 



rically 



rically 



rically 



rically 



liquid 



acid 



grin. 



grin. 



grm. 



grm. 

 A. 



er one decc 



grm. 



cm 3 



N. 







Filtration aft, 



mtation. 







00391 



00404 



00412 



+00013 



+00021 



86 



006 



00588 



00610 



00617 



+00022 



+00029 



109 



007 







Filtration afti 



B. 



?r two decantations. 







00196 



00202 



00202 



+00006 



+0-0006 



29 



005 



00196 



00190 



00193 



—0-0006 



—00003 



79 



004 



00391 



00405 



00409 



+00014 



+00018 



76 



005 



00391 



00398 



00403 



+0-0007 



+00012 



77 



010 





Filtration after 



C. 

 several decantations. 







00196 



00198 



00198 



+0-0002 



+0-0002 



39 



002 



00196 



00196 



00198 



0-0000 



+0-0002 



39 



005 



00196 



00200 



00199 



+0-0004 



+0-0003 



39 



007 



00196 



00197 



00197 



+0-0001 



+0-0001 



39 



009 



00196 



00191 



00190 



—00005 



—0-0006 



38 



005 



00196 



0-0197 



0-0195 



+0-0001 



—00001 



28 



006 



00391 



00398 



0-0399 



+0-0007 



+00008 



76 



£06 



00391 



00391 



0-0389 



0-0000 



—00002 



56 



006 



00588 



0-0598 



00598 



+0-0010 



+0-0010 



114 



007 



00588 



00590 



00591 



+0-0002 



+0-0003 



114 



005 



00789 



00763 



00774 



—00021 



—00010 



152 



005 



00980 



00960 



00974 



—00020 



—00006 



191 



006 





Filtration c 



i.fter addition o 



D. 



/ asbestos, 



without decantation. 





00196 





00200 





+0-0004 



38 



005 



00196 





00195 





—0-0001 



38 



005 



The adjustments of the amounts of thorium nitrate 

 necessary and permissible in precipitating unknown 

 amounts of fluoride by means of a series of partial pre- 

 cipitations and decantations, as described by Pisani, is a 



