ATOMIC WEIGHTS 197 



Eeducing these ratios with 



we have- 



General mean, Ba = 137.302, ± .0013 



This mean is probably too low, for the value from ratio 1 is affected 

 by the doubtful determinations of several early investigators. That 

 ratio, however, has the highest weight in the combination. Eejeoting 

 the first three values, the last four give a general mean of 



Ba = 137.363, ±.0025 



which will be adopted in subsequent computations. 



A few experiments are on record with reference to determining the 

 atomic weight of barium from the percentage of water in the hydrated 

 chloride. This method has been carefully investigated by Guye and 

 Tsakalotos,^ who conclude that the chloride in question is not suited to 

 the purpose. Their data give Ba = 139.5 approximately; while similar 

 data by Marignac give 136.5. The subject needs no further consideration 

 here. 



^ Journ. Chim. Phys., 7, 215. 1909. Marignac's figures are discussed in the second edition of 

 this work. 



