FLUORINE. bl 



(l.) CaF2 : CaSO^ : : i.o : 1.74493, d= .0002 

 (2.) NaF : Na,SO^ : : i.o : 1.6863, =t -0004 

 (3.) KF : KjSO^ : : I.O : 1.4991, ± -0007 

 (4.) BaFg : BaSO^ : : 1.0 : 1.3310, rh .0004 

 (5.) PbF.^ : PbSO^ : : 5.0 : 6. 1783, i .0002 



From these we get five values for F : 



From (I) F = 18.926, ± .009 



" (2) " = 19.050, zh .014 



" (3) " = 18.975. ± -032 



" (4) " = 18.993, ± -033 



«' (5) '• =- 19.092, rb .016 



General mean " = 18.984, ifc .0065 



If = 16, this becomes 19.027. 



Before leaving the subject of fluorine we must notice two 

 possible sources of error beyond the always to be considered 

 one of impurities in the materials employed. First, an in- 

 complete conversion of a fluoride into a sulphate would lead 

 to results tending to raise the atomic weight of fluorine. 

 On the other hand, the value for fluorine which has most 

 weight is that derived from calcium fluoride. But it was 

 shown under calcium that the atomic weight determined for 

 that metal was probably a trifle too high. This error, intro- 

 duced into our fluorine calculations, tends to lower our final 

 results. These two errors, then, if the}^ really exist, will, in 

 part at least, compensate each other. 



