232 PROCEEDINGS OP THE AMERICAN ACADEMY 



This fluoride was first prepared by Gay-Lussac and Thenard, and 

 afterwards described by Berzelius as a compound of manganese and 

 potassium ; but the latter established no ratio between the constit- 

 uents. 



An analysis of the soda salt which is precipitated under the same 

 conditions will by analogy furnish the formula MuFg. NaF. 



Another double fluoride of manganese and potassium has been ob- 

 tained by adding potassic fluoride to a solution of MnF.,. 3HF. A 

 white crystalline precipitate is immediately thrown down, which anal- 

 ysis shows to contain Mn and K in the ratio 1 : 4 respectively. This 

 double fluoride has identical properties with the preceding. 



Tetrajiuoride of Manganese, 3LiF^. AK^O. — (1) A black oxide of 

 manganese was prepared by exposing manganous carbonate to a dull 

 red heat for a considerable time. This oxide was proved to be 



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This oxide dissolves readily in hydrofluoric acid with the aid ot 

 heat, and the deep red solution, when evaporated to the crystallizing 

 point, deposits crystals on cooling. A larger crop of crystals is ob- 

 tained by carrying the solution to dryness in vacuo. (2) Pure per- 

 oxide of manganese is dissolved in hydrofluoric acid under j^ressure 

 with the aid of heat. On evaporating the solution red crystals are 

 obtained. 



In the following analysis, Mn was estimated, and the combined 

 weight of fluorine and water inferred from the loss. The water was 

 then determined in a second portion of the material by ignition with 

 plumbic oxide. The fluorine was thus indirectly ascertained: — 



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Properties. — Color, red by reflected, purjile by transmitted, light. 

 Crystallizes in the monoclinic system in rather long, narrow prisms. 

 These prisms consist in basal planes at the end of the ortho and klino 



