ATOMIC WEIGHTS 409 



This mean is near the values deduced from Meyer's and Christensen's 

 determinations, which are presumably the best. If it is applied to 

 Christensen's ratio, No. 7, it gives for the atomic weight of manganese 

 Mn = 54.933, which agrees well with the results obtained by Baxter and 

 Hines. From this we may fairly infer that the value for fluorine is 

 not far from the trutli. 



MANGANESE. 



The earliest experiments of Berzelius ^ and of Arfvedson ^ gave values 

 for Mn ranging between 56 and 57, and therefore need no farther con- 

 sideration here. The first determinations to be noticed are those of 

 Turner ^ and a later measurement by Berzelius,'* who both determined 

 gravimetrically the ratio between the chlorides of manganese and silver. 

 The manganese chloride was fused in a current of dry hydrochloric acid, 

 and afterguards precipitated with a silver solution. I give the MnCL 

 equivalent to 100 parts of AgCl in the third column : 



4.20775 grm. MnCL=: 9.575 grm. AgCl. 43.945 \ 



3.063 " = 6.96912 " 43.950 j^^^^^^^^ 



12.47 grains MnCl, = 28.42 grains AgCl. 43.878— Turner 



Mean, 43.924, ± .015 



Hence Mn = 55.07, Berzelius; or 54.87, Turner. 



Many years later Dumas ° also made the chloride of manganese the 

 starting point of some atomic weight determinations. The salt was fused 

 in a current of hydrochloric acid, and afterwards titrated with a standard 

 solution of silver in the usual way. One hundred parts of Ag are equiva- 

 lent to the quantities of MnCl, given in the third column : 



3.3672 grm. MnCL = 5.774 grm. Ag. 58.317 



3.0872 " 5.293 " 58.326 



2.9671 " 5.0875 " 58.321 



1.1244 " 1.928 " 58.320 



1.3134 " 2.251 " 58.321 



Mean, 58.321. ±: .001 



Hence Mn = 54.916. 



1 Poggend. Annalen, 8, 185. 1826. 



= Berz. Jahresbericht, 9, 136. 1829. 



-Trans. Roy. Soc. Edinb., 11, 143. 1831. 



*Lehrbuch, 5 Aufl., 3, 1224. 



= Ann. Chem. Phaim., 113, 25. 1860. 



