4- .56 Dr. Hare on the Fusion of Carbon. 



by oxygen gas, is very unfit tor the fusion oF cliarcoal, which 

 when exposed to heat and oxygen passes oft' in the form of 

 carbonous oxide, or carbonic acid gas ; — but the opposite is 

 true of the ignition of tlie deflagrator ; in producing which, 

 oxygen has httle or no agency, and with whose effects it can- 

 not materially interfere, both on account of the excessive rare- 

 faction, and the vapour of carbonaceous matter, produced by 

 the extreme heat. 



The fusion of plumbago by the former was readily effected 

 by me more than twenty years ago, as may be seen in my 

 memoir on the supply and application of the blowpipe. The 

 same result was subsequently accomplished by Proiessor Sil- 

 liman, and now, agreeably to the memoir before us, by Profes- 

 sor Vanuxem himself According to the analysis mentioned 

 in this memoir, in which plumbago is thus admitted to be fu- 

 sible, it differs from carbon only in containing three parts, in 

 a hundred, of iron. Upon what ground then has Professor 

 Vanuxem been so incredulous, respecting the fusibility of car- 

 bon, as to believe more readily that Dr. Macneven had ob- 

 tained from it a globule of iron, than that Professor Silliman 

 could accomplish its fusion ? 



Dr. Hays stated before the Academy of Natural Sciences, 

 at their last meeting in March, that at the time of sending to 

 Judge Cooper the globule analysed by Mr. Vanuxem, it was 

 represented as a product of mahogany charcoal*. Pro- 

 fessor Vanuxem has not as yet acknowledged himself, or Dr. 

 Macneven, to have fallen into any error in treating malleable 

 iron as a possible extemporaneous product of mahogany. He 

 has not even done me the honour of noticing the paper in 

 which it was demonstrated that, in so treating it, he had made 

 a mistake. We are of course to infer that he still adheres to 

 the position that wood charcoal may yield, during a transient 

 exposure to ignition, a globule of iron in its metallic form. 

 Under these circumstances, it must surprise every reader that 

 he does not by an analysis of mahogany charcoal endeavour 

 to prove that iron exists in it in such quantity, as that such a 

 ferruginous globule may be, in such manner, obtained from it. 

 If the negative proof founded on his neglect to analyse this 

 substance, on which the observations of Professor Silliman 

 were chiefly made, be combined with the positive evidence fur- 

 nished by ins own analysis, (that even in plumbago, which is 

 considered as a carburet of iron, this metal does not exist in 

 quantity adequate to have produced a globule principally fer- 

 ruginous, during a momentary ignition,) it seems to me that 



* Professor Macneven lias recently stated the same fact, in conversation 

 with the editor, September 1825. 



the 



