loft Mr. Lardner Vanuxem on [Fed. 



Exper. 4. — An impure specimen of plumbago from the same 

 locality gave numerous and large globules ; some of the size of 

 small shot; they readily formed; the majority of them were 

 translucent, shining, and of a light greenish-yellow, others were 

 dark coloured ; and some of them were dull externally. The 

 dark globules, as well as the surface of the mass. of plumbago 

 exposed to the flame, was attracted by the magnet ; some of the 

 light coloured ones were affected by the magnet, but only at the 

 point where they had been attached to their support, owing to 

 particles of the support adhering to them. During the combus- 

 tion of the plumbago, there were occasionally scintillations ; the 

 heated surface of tlie mass was brownish. 



A large globule of the lightest colour and magnetic only at 

 one point, melted with ease when the compound flux was used ; 

 it formed a transparent mass when hot, and opaque and milky 

 when cold. The black ones with the same flux were also fused ; 

 they were brownish when hot, and greenish when cold. They 

 were acted upon with great difficulty by caustic potash, and by 

 carbonate of soda. 



The analysis of this plumbago gave, 



Carbon 61-27 



Water 5.33 



T, ., ... 1 fSilex 10-10 



Residue by nicme- ^j^^.^^^ 3.30 



ration, colour of I 33-4 consist- ' q^j^^^ ^^ -^^^^ ^^^^ 



a duty yellowish f ing of ^ manganese 20-00 



i-^d J LLoss.. 0-10 



100-00 



Exper. 5. — A specimen of plumbago remarkably pure, from 

 near Bustletown, Penn. was tried with the blowpipe. The glo- 

 bules were formed with difficulty, probably owing to its foliated 

 texture, the fused parts spreading over the surface. The colour 

 in places was white and translucent ; in others so dark as to be 

 almost black. 



With the flux before mentioned, the fused matter was reduced 

 to a transparent glass. 



The analysis of this plumbago gave. 



Carbon 94-40 



Water 0-60 



P ., 1 . . ^ ^Silex 2-60 



^^^'^"^ ^y'"^;"^0 5-0 consist- fOxides of iron and 



ration, colour ^ ■ ^^ J manganese 1-40 



light brick red. J ^ (^Loss . f I'OO 



100-00 



