ESSAY V. 



ON MANGANESE, MANGANESIUM, OR MAGNESIA 

 VITRARIORUM. 1774. 



SECTION I. 



THOUGH the different species of manganese have attracted 

 the attention of chemists of late years, the result of their 

 experiments has gone no further than to disclose such of 

 their qualities as serve to distinguish them from other 

 minerals ; at least nothing has been published to elucidate 

 their nature any further, except a dissertation by Mr. 

 Westfeld, in the year 1767, in which this author first 

 examined their constituent parts. My experiments, however, 

 will show that his conclusions were too hastily made. I 

 think it unnecessary to enumerate all the different kinds of 

 manganese which I have examined, as they all agree in their 

 principal qualities. 



SECTION II. EFFECTS OF VITEIOLIC ACID ON MANGANESE. 



(a) 2 drms. of manganese, levigated in a glass mortar, 

 were digested with 1 oz. of diluted acid of vitriol for several 

 days. No effervescence ensued, neither had the acid lost any 

 of its taste, nor was the manganese diminished in quantity. 

 I, notwithstanding, filtered the liquor, and saturated the acid 

 with alkali of tartar, whence I obtained a yellowish white 

 precipitate, (b) Upon the remaining manganese I poured 



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