248 THE ATOMIC WEIGHTS. 



From the mean percentage of Cb^^Og, Cb = 93.217. If 

 O = 10, this becomes 93.431. 



From the mean between the extremes given for KjSO^, 

 Cb = 93.812. If = 16, this becomes 94.027. 



As Deville and Troost's * results for the vapor density of 

 the chloride and oxychloride agree fairly well with Cb = 

 94, we may adopt this value as approximately correct. 



ta:\^talum. 



The results obtained for the atomic weight of this metal 

 by Berzelius,t Rose,! and Hermann || may be fairly left out 

 of account as valueless. These chemists could not have 

 worked with pure preparations, and their data are suffi- 

 ciently summed up in Becker's " Digest." 



Marignac§ made four analyses of a pure potassium fluo- 

 tantalate, and four more experiments upon the ammonium 

 salt. The potassium compound, K/PaF^ was treated with 

 sulphuric acid, and the mixture was then evaporated to dry- 

 ness. The potassium sulphate was then dissolved out by 

 water, while the residue was ignited and weighed as Ta^Oj. 

 100 parts of the salt gave the following quantities of Ta205. 

 andK.SO, : 



Ta^Oy A', so,. 



56.50 44-37 



56.75 44-35 



56.55 44-22 



56.56 44.24 



Mean, 56.59, z^ .037 Mean, 44.295, ± .026 



* Comptes Rend., 56, 891. 1863. 



t Poggend. Annal., 4, 14. 1S25. Lclirbuch, 3, 1209. 



X Poggend. Annal., 99, 80. 1856. 



II Journ. fiir Prakt. Chem., 70, 193. 1857. 



\ Archives des Sci. Phys. et Nat., 26, 89, serie 2. 1866. 



