468 Scientific Intelligence. [Dec. 



III. On the Fusion of Charcoal f GraphitCi Anthracite^ and the Diamond. 

 By Professor Silliman. 



{Concluded from p. S 1 6.) 



In a second letter immediately succeeding that already given, dated 

 April 15, 1823, Dr. Silliman states:— 



Having last year caused to be constructed an aparatus, capable 

 of containing fifty-two gallons of gas, for the supply of your com- 

 pound, or oxy-hydrogen blow-pipe, 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. Al- 

 though their being non-conductors, would be no impediment to the 

 action of the blow-pipe flame on them, still, obvious considerations 

 have always made me consider the success of such experiments as 

 very doubtful. I allude, of course, to the combustibility of these bo- 

 dies, from which we might expect that they would be dissipated 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 consum- 

 ed, that the diamonds were speedily displaced 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 dazzling, that, although through green glasses I could 

 steadily inspect the focus, it was impossible to distinguish the dia- 

 mond in the perfect solar brightness. This mode of conducting the 

 experiment, proved, however, perfectly manageable ; and a large 

 dish, placed beneath, secured the diamonds from being lost (an acci- 

 dent which I had more than once met with), when suddenly displaced 

 by the current of gas ; as» however, the support was not combustible, 

 it remained permanent, except that it was melted in the whole region 

 of the flame, and covered with a perfect white enamel of vitreous 

 lime. The experiments 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 

 remove them from the heat, at very short intervals. They exhibited, 

 however, marks of incipient fusion. My experiments were performed 

 upon small wrought diamonds, on which there were numerous po- 

 lished facets, presenting extremely sharp and well-defined solid edges 

 and angles. These edges and angles were always r(»unded and gene- 

 rally obliterated. The whole surface of the diamond lost its conti- 

 nuity, and its lustre was much impaired ; it exhibited innumerable very 

 minute indentations, and intermediate and corresponding salient points ; 

 the whole presenting the appearance of having been superficially 

 soflened, and indented by the current of gas, or perhaps of having had 

 its surface unequally removed, by the combustion. In various places, 

 near the edges, the diamond was consumed, with deep indendations, 

 and occasionally where a fragment had snapped off, by decrepitation, 

 it disclosed a conchoidal fracture and a vitreous lustre. These results 

 were nearly uniform, in various trials ; and every thing seems to indi- 

 cate that were the diamond a good conductor, it would be melted by 

 the deflagrator ; and were it incombustible, a globule would be ob- 

 tained by the compound blow-pipe. 



In one experiment, in which I used a support of plumbago, there 



