80 THE ATOMIC WEIGHTS. 



1.686 

 1.683 

 1.685 



Mean, 1.6S47, zb .0006 



The weighings published by Dumas are as follows : 



•777 gi"™- NaF give 1.312 grm. Na^SO^. Ratio, 1.689 

 1.737 " 2.930 " " 1.687 



Mean, 1.688, zh .0007 



The general mean of both series is 1.6863, ± .0004. 



Dumas also gives experiments upon potassium fluoride. 

 The quantity of sulphate formed from one gramme of flu- 

 oride is given in the last column : 



1.483 grm. KF give 2.225 g^n^- KgSO^. 1.5002 



1.309 " I. 961 " I. 4981 



Mean, 1.4991, =h .0007 



The ratios for the fluorides of lead and of barium are due 

 entirely to Louyet. One gramme BaFg gave of BaS04: 



1-332 

 1-331 

 1-330 



Mean, 1.331, ± .0004 



With the lead fluoride a new method of treatment was 

 adopted. The salt was fused, powdered, dissolved in nitric 

 acid, and precipitated by dilute sulphuric acid. The evap- 

 oration of the fluid and the ignition of the sulphate was 

 then effected without transfer. Five grammes of fluoride 

 were taken in each operation, yielding of sulphate : 



6.179 



6.178 

 6.17S 



Mean, 6.1783, ih .0002 



We now have five ratios to calculate from, as follows : 



