1826.J Anthracite, Plumbago, Sjc. 109 



Similar experiments were made with plumbago from several 

 other localities, the results of which were no wise different, and 

 therefore need no further mention. 



Exper. 6. — A piece of charred mahogany, during its combus- 

 tion by the compound blowpipe, presented numerous small 

 imperfect globviles, owing to the force of the flame, which dissi- 

 pated their support before they had time to form or to accumu- 

 late to any considerable size ; many of them adhered together, 

 ramifying like flos fori, which they resembled ; they were 

 collected by placing a dish under their support. By the com- 

 pound flux, they readily fused into a transparent glass. 



Exper. 7. — A quantity of lamp-black was pressed into a mould 

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

 about three-fourths of an inch in diameter, and half an inch in 

 thickness; it weighed seven grammes. This cylinder of lamp- 

 black was subjected to the blowpipe. It wasted away gradually 

 without forming any globules or fused matter, visible to the 

 naked eye or to the microscope. The heat was equally as 

 intense in this experiment as in all the other instances, and no 

 condition was wanting to produce the same effects, except the 

 difference of composition. After burning the lamp-black for as 

 long a time as was thought necessary to make the experiment a 

 fair one, it was again weighed, and found to have lost four 

 grammes, -^-^, for it weighed but two grammes, ^Vo- 



Five grammes of the same lamp-black heated in an open pla- 

 tina crucible, left after its incineration one centigramme of white 

 ashes, equal to -^ of the mass. 



From the analyses of the substances used by Prof. Silliraan, 

 from which the globules were obtained, it appears that they all 

 contain foreign matter, as silex, iron, manganese, and some of 

 them also alumine; that when lamp-black was used which con- 

 tained but -s-^p. of fixed impurities, no distinct globule or melted 

 matter was formed ; although the heat was sufficiently great, 

 and the combustion slow enough to admit of the forming of glo- 

 bules, if their production was owing to the fusion of carbon, and 

 not to extraneous matter. From my own experiments I always 

 found that the more impure the substance was, the more nume- 

 rous and the larger were the globules produced. 



All the globules from the different kinds of substances used, 

 were readily fused by the compound flux, and underwent little 

 change when it was not used ; although the heat was, in this 

 case, of longer continuance. Matter similar to the impurities 

 discovered in the substances used was detected in them. 



From these facts it would appear, that the globules produced 

 from the combustible substances operated upon, did not arise 

 from the fusion of their carbon, since they can otherwise be 

 accounted for; particularly as no experiment has been made 

 which unequivocally leads to that conclusion. The experiment 



