326 On the Oxide of Manganese of Naygug. 



The gas obtained in this experiment, when passed through 

 lime water, did not injure its transparency, but gave it the 

 property of blackening solutions ot" lead. 



The nitric solution was mixed with carbonate of potash : ' 

 it formed an abundant white precipitate with a brisk disen- 

 gagement of carbonic acid gas. We heated it lightly m 

 order to drive off the excess of this acid; and we separated 

 the precipitate, which, upon being well washed and dried, 

 weighed 7-,V graunncs. The difference between our results 

 and those of AI. Klaproth seems to arise from the manga- 

 nese uicd bv us having been vcrv pure, while that employed 

 by M. Klaproth probably contained carbonate of lime, 



M. Klaproth endeavoured' to form a combination between 

 sulphur and the oxide of manganese at the minimum, in 

 order to make comparative experiments, and he discovered 

 that the artificial sulphuret of manganese, when no atom of 

 sulphuretted hydrogen could enter into it, had the same cha- 

 racters as the natural sulphuret. In order to follow his ex- 

 periments, I calcined in a retort, the aperture of which com- 

 municated with a balloon filled with lime water, 7-4 grammes 

 of carbonate of manganese obtained by precipitation by means 

 of carbonate of potash. 



The carbonic acid gas began to disengage Itself before the 

 retort was red, and at the end of a quarter of an hour's cal- 

 cination the disengaojement ceased. The oxide contained in 

 the retort was slightly coloured, at least at its surface. We 

 introduced into the retort, while yet warm, two grammes of 

 flowers of sulphur, and we agitated it in order to produce a 

 mixture; the mass melted, and a considerable quantity of 

 sulphur was sublimed. As soon as the sublimation of the 

 sulphur ceased, the mass, when taken out of the retort while 

 warm, took fire on exposure to the air in th(> manner of 

 pyrophorus. It was green, like the natural sulphuret in 

 powder; and it weighed 5*9 grammes. This artificial sul- 

 phuret dissolved in weak nitric acid with effervescence 

 and a disengagement of sulphuretted hydrogen gas ; but it 

 leaves more sulphur as a residue than natural sulphuret. 



The following is the manner in which M. Klaproth ex- 

 plains the disengagement of the hydrogen gas which takei 



place 



