172 Contributions towards [Sept. 



Article III. 



Contributions towards a Chemical Knowledge of Manganese. 



By Dr. John.* 



Though manganese was known in the .remotest times, and 

 though after Bergman had shown that it contained a pecu- 

 liar metal, several distinguished chemists occupied themselves 

 with experiments upon it, yet it is one of the metals respecting 

 which our knowledge is most defective. Indeed, we may say 

 that it never has been described in a state of purity. This con- 

 sideration has induced me to make choice of it as an object of 

 experiment. My labours on it have of necessity been so various, 

 and my observations on it so numerous, that it would fatigue my 

 readers too much were I to publish the whole at once. I shall 

 therefore lay them before the world at different times, and in 

 separate dissertations. 



I. Purifying of the Oxide of Manganese. 



This, which is accomplished with no small difficulty, must 

 occupy us in the first place. That chemists have hitherto 

 attained the means of purifying manganese only imperfectly, is 

 obvious from the many processes proposed, all differing so much 

 from each other. 



It is not only to the separation of the iron always contained in 

 the mixture to which we ought to pay attention; copper, also, 

 and not unfrequently lead, together with several earths, are to be 

 found in several of the ores ol manganese. In particular, I have 

 found them in the purest grey Saxon manganese. 



For the separation of the iron from manganese we do not, it 

 is true, want processes ; but I have examined them with accu- 

 racy, and have not found any of them singly fully to answer 

 the intended purpose. 



Gehlen's well known, and generally practised, method of 

 separating iron from all metals which iorm a soluble salt with 

 succinic acid, by precipitating the iron from its solution by 

 means of an alkaline succinate, leaves nothing farther to be 

 desired in respect of accuracy; but if we consider the high price 

 of succinic acid, and the continually diminishing quantity of 

 amber from which it is procured, the matter will appear in 

 another light, and induce us to look out for a more convenient 

 method. 



* Translated from Gehlen's Journal fur die Chemie und Plivsik Drifter Band 

 Sid. ii. 53. 



