Browning and Flint — Tellurium Dioxide. 



113 



quently acetic acid, added with great care. After standing 

 over night, the liquid was decanted through the asbestos 

 of a Gooch crucible, and the precipitate transferred and 

 washed with cold water, and dried to constant weight at 

 about 105°. In Table I, experiments 1 to 4, are gathered the 

 results obtained. 



Table I. 





Te0 2 taken 



Te0 2 found 



Error 





grm. 



grm. 



grm. 



(1) 



0-2002 



0-2000 



— 0-0002 



(2) 



0-2019 



0-2017 



— 0-0002 



(«) 



0-290.4 



0-2002 



— 0-0002 



(4) 



0-2006 



0-2004 



— 0-0002 



(5) 



0-2011 



0-2010 



—o-oooi 



(6) 



0-2003 



0-2003 



o-oooo 



In experiments 5 and 6, one and one-half cubic centimeters 

 of ten per cent potassium hydroxide solution were used to 

 dissolve the dioxide, instead of hydrochloric acid. The solu- 

 tion was then acidified slightly with hydrochloric acid, and the 

 determinations completed from this point as before. The 

 results seem to be equally good. 



Next, weighed amounts of basic nitrate were dissolved in 

 two cubic centimeters of hydrochloric acid. The small quan- 

 tity of nitric acid holds up a little of the tellurium* and con- 

 sequently before dilution resort was had to evaporation to 

 remove as much of the free acid as possible. This had to be 

 done with extreme care, since the least tendency on the part 

 of the solution to boil was accompanied by the volatilization 

 of the tetrachloride formed. With a not unreasonable amount 

 of care, however, good results were obtained. In all of the 

 experiments of Table II the dilution was with hot water, 

 two hundred cubic centimeters being sufficient, but in several 

 the treatment was varied, as given below. 



Table II. 





2Te0 2 .HN0 3 



Te0 2 





taken 



theory 





grm. 



grm. 



(1) 



0-2508 



0-2094 



(2) 



0-2501 



- 0-2088 



(*) 



0-2521 



0-2105 



(4) 



0-2500 



0-2088 



« 



0-2537 



0-2118 



(6) 



0-2510 



0-2096 





*Gutbier, 



Studien 



Te0 2 





found 



Error 



grm. 



grm. 



0-2079 



— 0-0015 



0-2086 



— 0-0002 



0-2101 



— 0-0004 



not completed 





0-2115 



— 0-0003 



0-2091 



— 0-0005 



Studien liber das Tellur, 46. 



