129 



Hence Mn = 54.785, ±: .031. 



Mean, 57.608, db .008 



This method of v. Hauer's, which seemed to give good 

 results with cadmium, is, according to Schneider,* inappli- 

 cable to manganese; for the reason that the sulphide of the 

 latter metal is liable to be contaminated with traces of oxy- 

 sulphide. Such an impurity would bring the atomic weight 

 out too high. The results of two different processes, one 

 carried out by himself and the other in his laboratory by 

 Rawack, are given by Schneider in this paper. 



Rawack reduced manganoso-manganic oxide to manga- 

 nous oxide by ignition in a stream of hydrogen, and weighed 

 the water thus formed. From his weighings I get the values 

 in the third column, which represent the MugO^ equivalent 

 to one gramme of water : 



4.149 grm. MngO^ gave 0.330 grm. H.^O. 12.5727 



649 



356 

 9445 



584 



Hence Mn = 53.911, ± .026. 



.0034 



Here the most obvious source of error lies in the possible 

 loss of water. Such a loss, however, would increase the 

 apparent atomic weight of manganese ; but we see that 

 the value found is much lower than that obtained either by 

 Dumas or v. Hauer. 



Poggend. Annal., 107, 605. 



