130 Professor Sitliman on Ihe Fusion of Plumbago. 



from carbon, volatilized in a white state oven from cliarcoal 

 itself, anil condensed in a form analogous to the diamond. 

 The rigorous and obvious experiments necessary to determine 

 this question it is not now practicable for me to make, and I 

 must in the mean time admit the possibility that alkaline and 

 earthy impurities may have contributed to the result. 



In one instance contiguous to, but a little aside from, the 

 cliarcoal points,, I obtained isolated daik coloured globules of 

 melted charcoal, analogous to those of plumbago. 



The opinion which I formerly stated as to the passage of a 

 current from the copper to the zinc pole of the deflagrator, is 

 in my view fully confirmed. Indeed, with the protection of 

 green glasses, my eyes are sufficiently strong to enable me tt> 

 look steadily at the flame during the whole of an experiment, 

 and I can distinctly observe matter in different forms passing 

 to the zinc pole, and collecting there, just as we see dust or 

 other small bodies driven along by a common wind ; there is 

 also an obvious tremor, produced in the copper pole, when the 

 instrument is in vigorous action, and we can perceive an evi- 

 dent vibration produced, as if by the impulse of an elastic fluid 

 striking against the opposite pole. 



If, however, the opinion which yon formerly suggested to 

 me, and which is countenanced by many facts, that the poles 

 of the deflagrator are reversed, the copper being positive and 

 the zinc negative, be coiTect, the phenomenon, as it regards the 

 course of the current, will accord perfectly well with the re- 

 ceived electrical hypothesis. 



The number of unmelted substances being now reduced to 

 two, namely, the anthracite and the diamond, you will readily 

 suppose I did not neglect to make trial of them : as, however, the 

 diamond is an absolute nonconductor and the anthracite very 

 little better, I cannot say I had any serious hopes of success. 

 I have made various attempts, which have failed, and after losing 

 two diamonds, the fragments being thrown about with a strong 

 decrepitation, I have desisted froiii the attempt, having, as I 

 conceive, a more feasible project in view. 



I trust you will not consider the details of the preceding 

 pages as being too minute, provided the subject appears to 

 you as interesting as it does to me. The fusion of charcoal 

 and of plumbago is sufficiently remarkable; but the evident 

 approximation of the material of these bodies towards the con- 

 dition of diamond, from wliich they differ so remarkably in 

 their physical properties, afff)rds, if I mistake not, a striking 

 confirmation of some of our leadinj^ chemical doctrines. 



XXVII. Ex- 



