Dr. ILu'e on the Fusion of Varhon. 4-57 



the late memoir of Professor Vanuxem tends to prove the fal- 

 lacy of that already published by him, much more than it dis- 

 proves any of the allegations of Professor Silliman. 



Mr. Vanuxem justifies himself foi resorting to the com- 

 pound blowpipe, in order to invalidate results obtained by an 

 instrument extremely different in its character, by saying that 

 he has done so in obedience to a suggestion of Professor Silli- 

 man. If any evidence be requisite to prove that Professor 

 Silliman never intended to sanction such a procedure, it may 

 be found in the following passage, concluding his observations 

 on the results obtained by this instrument. He says, 



" I would add, thai for the mere fusion of jilumbago the 

 blowpipe is much preferable to the deflagrator; but a variety 

 of interesting phaenoinena, both in relation to the plumbago 

 and the charcoal, are to be exhibited by the latter, but not 

 by the former." 



In another place he observes, " Were the diamond a good 

 conductor, it would be melted by thedeflagrator; and were it 

 incombustible, a globule would be obtained by the compound 

 blowpipe." 



It is evidently, therefore, the opinion of the author of this 

 passage, that carbon, even in its most incombustible state, as 

 in that of the diamond, is still too combustible to yield glo- 

 bules with the instrument which Professor Vanuxem has used 

 for that purpose. 



To conclude : It a}ipears to nie that the grounds upon which 

 the results of Professor Silliman have been assailed by INIr. 

 Vanuxem are utterly untenable. The animadversions of his 

 first memoir were founded on an analysis of a globule, which 

 being proved by himself to be malleable iron, was of course 

 erroneously treated as an extemporaneous product from a mi- 

 nute portion of wood charcoal. In the memoir now under 

 consideration he adtluces exjjeriments performed by the com- 

 pound blowpipe, in order to invalidate observations made by 

 means of an instrument of a very different character. 



So far as respects the curious and interesting pha^nomenon 

 of a projection arising on the charcoal attached to the nega- 

 tive pole of the def^agrator, I am fiilly prepared to bear wit- 

 ness to the correctness of the descri])tion given by Professor 

 Silliman. There has been no conclusive analytic demonstration 

 that the excrescence which thus arises is pure carbon; and 

 had it been supposed, or proved, to contain a minute portion 

 of iron, it would not have surprised me. 



With res})ect to the colourless globules resembling dia- 

 mond, Professor Silliman has never treated them as carbon 



Vol. 66. No. 3S'2. Dec. 182.5. .'< M unquestionably; 



