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XXVIT. Experimoils upon Diamond, Anthracite, and Plum- 

 bago, ivith t/ie compound Blonpipe : in a Letter addicsscd to 

 Professor Robert Hake, M. D. by Professor Silliman, 

 dated Yale College, April 15, 1823.* 



TITAVING last year caused to be constructed an apparatus, 

 -*■•*■ capable of containing fifty-two gallons of gas, for the 

 supjily of jour comiiound or oxy-hydrogen blowpipe, and 

 capable of receiving a strong impulse from pressure, I have 

 been intending, as soon as practicable, to subject the diamond 

 and the anthracite to its intense heat. Although their being 

 non-conductors would be no impediment to the action of the 

 blowpipe flame on them, still obvious considerations have 

 alwaj's made me consider the success of such experiments as 

 very doubtful. I allude of course to the combustibility of these 

 bodies, from which we might expect that they would be dissi- 

 pated by a flame sustained by oxygen gas. 



My first trials were made by placing small diamonds in a 

 cavity in charcoal; but the support was in every instance 

 so rapidly consumed, that the diamonds were speedily dis- 

 placed by the current of gas. I next made a chink in a piece 

 of solid quick lime, and crowded the diamond into it; this 

 proved a very good support, but the effulgence of light was so 

 tiazzling, that, although through green glasses I could steadily 

 inspect the focus, it was impossible to distinguish the diamond 

 in the perfect solar brightness. This mode of conducting the 

 experiment proved, however, perfectly manageable, and a 

 large dish jilaced beneath secured the diamonds from being 

 lost (an accident which I had more than once met with) when 

 buddenly displaced by the current of gas : as, however, the 

 supjxjrt was not combustible, it remained permanent, except 

 that it was melted in the whole region of the flame, and covere(l 

 with a perfect white enamel of vitreous lime. The experi- 

 ments were frequently suspended, to examine the effect on the 

 diamonds. They were found to be rapidly consumed, wasting 

 so fast, that it was necessary, in order to examine them, to re- 

 move them from the heat at very short intervals. They ex- 

 hibited, however, marks of incipient fusion. My experiments 

 were performed upon small wrought diamonds, on which there 

 were iniinerous polished facets, presenting extremely sharp and 

 well defined solid edges and angles; these edges and angles were 

 always rounded and generally obliterated. The whole surface 

 t)f the diamond lost its continuily, and i(s lustre was much im- 

 paired; it exhibited innumerable very minute indentations anil 



* Sillinian's Journal, vol. vi, p. ."! ID. 



11 2 inter- 



