282 THE ATOMIC WEIGHTS. 



MANGANESE. 



The earliest experiments of Berzelius* and of Arfvedsonf 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 afterwards precipitated with a silver solution. I give the MnCl.^ 

 equivalent to 100 parts of AgCl in the third column : 



4.20775 grm. MnCl,=r 9.575 grm. AgCl. "^3-945 "t ^5^^^^,;^, 



3.063 " = 6.96912 " 43.950/ 



12.47 grains MnClj ^ 28.42 grains AgCl. 43.878— Turner. 



Mean, 43.924, ± .015 



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^ 



3.0872 



2.9671 " 



I. 1244 



1.3134 



Mean, 58.321, i .001 



An entirel.y different method of investigation was followed by von 

 Hauer,^ who, as in the case of cadmium, ignited the sulphate in a stream 

 of sulphuretted hydrogen, and determined the quantity of sulphide thus 

 formed. I subjoin his weighings, and also the percentage of MnS in 

 MnSO^ as calculated from them : 



4.0626 grm. MnSO^ gave 2.3425 grm. MnS. 57.66o per cent. 



4.9367 " 2.8442 " 57.613 " 



5.2372 " 3-0192 " 57.649 " 



7.0047 " 4-0347 " 57.600 



4.9175 " 2.8297 " 57-543 " 



4-8546 " 2.7955 " 57.585 " 



4.9978 " 2.8799 " 57-625 " 



46737 " 2.6934 " 57-629 " 



4.7240 " 2.7197 " 57-572 



Mean, 57.608, ± .008 



*Poggend. Annalen, 8, 185. 1826. 

 t Berz. Jahresbericht, 9, 136. 1829. 

 J Trans. Roy. Soc. Edinb., ir, 143. 1831. 



I Lehrbuch, 5 Aufl., 3. 1224. 



II Ann. Chem. Pharm., 113, 25. i860. 

 HJouru. fiir Prakt. Cheni., 72, 360. 1857. 



