406 SMITHSONIAN MISCELLAKEOUS COLLECTIONS VOL. 54 



For the ratio between the two sodium salts we have experiments by 

 Dumas. Louyet and Moissan. According to Louyet, one gramme of 

 XaF gives of Na,SO,— 



1.686 



1.683 



1.685 



Mean, 1.6847, ± .0006 

 Hence F = 19.06. 

 The weighings published by Dumas are as follows : 



.777 grm. NaF gave 1.312 grin. NajSO^. Ratio, 1.689 



1.737 " 2.930 " " 1.687 



Mean, 1.G88, it .0007 



Hence F = 19.08. 



Moissan says only that five experiments with sodium fluoride gave 

 F = 19.04 to 19.08. This was calculated with Na = 23.05 and S = 32.074. 

 Hence, reckoning backward, the two values give for the standard ratio — 



1.6889 

 1.6873 



Mean, 1.6881 

 Hence F = 19.07. 

 Giving this equal weight with Dumas' mean, we have — 



Louyet 1.6847, ± .0006 



Dumas 1.688, ± .0007 



Moissan 1.6881, ± .0007 



General mean 1.6867, ± .00038 



Dumas also gives experiments upon potassium fluoride. The quantity 

 of sulphate formed from one gramme of fluoride is given in the last 

 column : 



1.483 grm. K.F gave 2.225 grm. KjSOi. 1.5002 



1.309 " 1.961 " 1.4981 



Mean, 1.4991, ± .0007 

 Hence F = 19.02. 



The ratio between barium fluoride and barium sulphate was measured 

 by Louyet and Moissan. According to Louyet, one gramme of BaF, 

 gives of BaSO^^ — 



1.332 

 1.331 

 1.330 



Mean, 1.3?,1, ± .0004 

 Hence F = 19.01. 



