on AiUk/aciie, Plumbago, S)-c. 165 



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 



Tj • 1 1 • • •>. rSilex 10*10 



Residue by mci-^ ai • .. ^ 



r \ Alum me . . . 3-20 



Deration, co- I „„ . . ^. r J /^ • 1 c ■ 



lour of a dirty >33-4 consistmg of ^ Oxides of n-oni^^,^^ 



yellowish-red J /"'^ manganesei 



^ -* t_Loss -10 



100-00 

 Experiment 5. — A specimen of plumbago remarkably pure, 

 from near Bustlelown, Pennsylvania, was tried with the blow- 

 pipe. The globules 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 re- 

 duced to a transparent glass. 



The analysis of this plumbago gave 



Carbon 94-40 



Water 0-60 



T> • 1 , • • _ ( Silex 2-60 



JiesKlue by mci-^ \ /-» • 1 n • ^ 



1 f r- r^ -4^- c J Oxides 01 iron / , , ^ 



neration, colour \ 5-0 consisting 01 < , s 1-40 



light brick-red J / /"^^ manganese [ 

 *= I, Loss 1-00 



100-00 

 Similar experiments were made with plumbago from several 

 other localities ; the results of which were nowise different, and 

 therefore need no further mention. 



Experiment 6. — A piece of charred mahogany, during its 

 combustion by the compound blowpipe, presented numerous 

 small imperfect globules, owing to the force of the flame, which 

 dissijiated their support befoie they had time to form or to 

 accumulate to any considerable size : many of them adhered 

 together, ramifying like^os_/f?n, which they resembled. They 

 were collected by placing a dish under their support. Bv the 

 compound flux they readily fused into a transparent glass. 



Experiment 7. — A quantity of lampblack was pressed into 

 a mould with great force, and made to assume the form of a 

 cylinder of about 3-4ths of an inch in diameter and half an 

 inch in thickness ; it weighed seven grammes. This cylinder 

 of lampblack was subjected to the blowpipe. It wasted away 

 gradually, without forming any globules or fused matter visi- 

 ble 



