1826.1 Anthracite, Plumbago, 3)'c. 107 



Carbon 90-03 



Water 4-90 



Residue by incine-"^ TSilex 2- 14 



ration, which was ! 5*07 consist-J Oxides of iron and 



of a light brick [ ing of "^| manganese ...... 2-50 



red J l.Loss.7 0-43 



100-00 



Another specimen from the same locality, whose colour was 

 a little different, being of a deeper black, and which was not 

 tried with the blowpipe, gave, 



Carbon 77-70 



Water 6-70 



Residue by incine-"^ ("Silex 8-50 



ration, colour the ! 15-60 consist- J Oxides of iron and 

 same as the for- [ ing of | manganese ..... 7-10 

 mer J l_Alumine . . , Trace 



100-00 



Exper. 3. — A specimen of plumbago from Borrowdale, of 

 great purity, as judged by its external characters and mechani- 

 cal properties, was subjected to the blowpipe ; the globules 

 began to form immediately and in great number, attended occa- 

 sionally by scintillations, owing to the combustion of iron ; the 

 globules were small ; the greater part of them were black, 

 opaque, and of great lustre ; others were dull, of a brownish 

 colour, and feebly translucent ; almost all of them were 

 attracted by the magnet. The surface of the heated part of the 

 plumbago was brownish. 



The globules, though acted upon with great difficulty by soda, 

 and by potash, readily yielded to the compound iiux, and 

 formed a limpid yellowish glass. A large globule, by repeatedly 

 heating it with carbonate of soda, and plunging it into water, 

 became rough, and finally opened in the centre ; it then dis- 

 solved in nitro-muriatic acid. By evaporating the liquor to 

 dryness, the yellow colour of the iron was very manifest ; acidu- 

 lated water took it up, leaving a white substance like silex, 

 floating in the liquor. 



The analysis of this plumbago gave, 



Carbon 88-37 



Water 1-23 



rSilex 5-10 



Residue byincine-*^ -.r.^ ■ . Alumine 1-00 



ration, colour, yel- > • o- f '^ ^^ide*^ of iron and 



lowish brick red. .J '"^ ^ manganese 3-60 



Loss 0-70 



100-00 



