1 32 Professor Silliman's Experiments xvith the Blo'dpipe 



intermediate and corresponding salient points ; the whole pre- 

 senting the appearance of having been superficially softened and 

 indented by the current of gas, or perhaps of having had its sur- 

 face unequally removed by the combustion. In various places, 

 near the edges, the diamond was consumed, with deep indenta- 

 tions, 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 indicate that, were the diamond a 

 good conductor, it would be melted by the deflragator, and 

 were it incombustible, a globule would be obtained by the 

 compound bloA\^ipe, 



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

 there were some interesting varieties in the phjenomena. The 

 plumbago being a conductor, the light did not accumulate as 

 it did when the support was lime, but permitted me distinctly 

 to see the diamond through the whole experiment. It was 

 consumed with great rapidity ; a delicate halo of blueish light, 

 clearly distinguishable from the blowpipe flame, hovered over 

 it; the surface appeared as if softened, numerous distinct 

 but very minute scintillations were darted from it in every di- 

 rection, and I could see the minute cavities and projections 

 which I have mentioned forming every instant. In this ex- 

 periment I gave the diamond but one heat of about a minute; 

 but on examining it with a magnifier, I was sin-prised to find 

 that only a very thin layer of the gem not much thicker than 

 writing paper remained, the rest having been burnt.* 



I subjected the anthracite of "V^'^ilkesbarre, Penn., to similar 

 trials, and, by heating it very gradually, its decrepitation was 

 obviated. It Avas consumed with almost as much rapidity as 

 the diamond, but exhibited, during the action of the heat, an 

 evident appearance of being superficially softened; I could 

 also distinctly see, in the midst of the intense glare of light, 

 very minute globules forming upon the surface. These, when 

 examined by a magnifier, proved to be perfectly white and 

 limpid ; and the whole surface of the anthracite exhibited, like 

 the diamond, only with more distinctness, cavities and pro- 



* In the Phil. Mag. for November 1821, vol. Iviii, page 386, 1 observe the 

 following notice by Mr. John Murray: — " By repeatedly exposing a diamond 

 to the action of the oxy-hydrogen blowpipe in a nidus of magnesia, it be- 

 came as black as charcoal, and split into fragments which displayed the con- 

 choidal (vactuxe. 



" It will be found, that this gem affixed in magnesia, soon flies off in mi- 

 nute fragments, exhibiting the impress of the conchoidal form. 



'' In lately exposing the diamond, fixed on a support of pipe-claj', to the 

 ignited gas, I succeeded in completely iii/lciiti)ig it;— examined after the 

 experiments, it exhibited proofs of having undci-goncfusiun." 



jeclions 



