ON MANGANESE 



97 



ADDITIONAL REMARKS UPON MR. SCHEELE'S ANALYSIS 

 OF MANGANESE. BY GUSTAVUS v. ENGESTROM. 



The experiments I made on manganese and its colour 

 seem to differ in some measure from Mr. Scheele's. Hence 

 it will perhaps appear how difficult it is to measure the 

 degree of fire in experiments with the blowpipe. 



I melted manganese and borax together upon charcoal 

 by means of the blowpipe. The glass at first assumed the 

 common colour of manganese ; but this colour I destroyed 

 without any addition, and imparted it again to the glass ; 

 and this I did repeatedly to the same globule without adding 

 anything. During the operation I observed the following 

 phenomena : 



(1) If I took a small quantity of manganese, the colour 

 was light ; if a larger portion, it became so dark as to appear 

 black. This dark or light colour, which manifested itself 

 during the first melting, appeared again in a second operation 

 upon the same mass. 



(2) Manganese, on being melted with borax, unites with 

 a violent effervescence, which, however, ceases as soon as the 

 manganese is dissolved. 



(3) If the glass of borax was coloured by manganese, 

 and I wished to make the colour disappear, I always directed 

 the blue flame of the candle upon the glass, and that equally 

 and constantly, but not very violently. As soon as I blew 

 more faintly, and allowed the brown flame to touch the place, 

 the glass grew dark again. According as the globule was 

 larger or smaller, more or less coloured, it required a longer 

 time to make the colour disappear. About the time when 

 the glass becomes colourless, a kind of a section or partition 

 is observed in it ; and as soon as the colour disappears the 



