DIAMONDS. 229 



carefully deposited on a slide, and examiued under the microscope. 

 Along with numerous pieces of black diamond are seen transparent, 

 colorless pieces, some amorphous, others with a crystalline appearance, 

 as I have attempted to reproduce in diagrams. Although many frag- 

 ments of crystals occur, it is remarkable that I have never seen a com- 

 plete crystal. All appear broken up, as if on being liberated from the 

 intense pressure under which they were formed they burst asunder. I 

 have direct evidence of this phenomenon. A very fine piece of artificial 

 diamond, carefully mounted by me on a microscopic slide, exploded 

 during the night and covered my slide with fragments. This bursting- 

 paroxysm is not unknown at the KijT^berley mines. 



On the screen I will project fragments of artificial diamond, some 

 lent me by Professor Roberts- Austen, others of my own make, while 

 on the wall you will see drawings of diamonds copied from M. Moissan's 

 book on the electric furnace. Unfortunately these specimens are all 

 microscopic. The largest artificial diamond, so far, is less than 1 milli- 

 meter across. 



Laboratory diamonds burn in the air before the blowpipe to carbonic 

 acid, and in luster, crystalline form, optical proj)erties, density, and 

 hardness they are identi(;al with the natural stone. 



Many circumstances point to the conclusion that the diamond of the 

 chemist and the diamond of the mine are strangely akin as to origin. It 

 is conclusively proved that the diamond has not been formed in situ in 

 the blue ground. The diamond genesis must have taken place at great 

 depths under enormous pressure. The explosion of large diamonds on 

 coming to the surface shows extreme tension. More diamonds are 

 found in fragments and splinters than in perfect crystals, and it is 

 noteworthy that although many of these splinters and fragments are 

 derived from the breaking up of a large crystal, yet in no instance 

 have pieces been found which could be fitted together. Does not this 

 fact point to the conclusion that the blue ground is not their true 

 matrix? Nature does not make fragments of crystals. As the edges 

 of the crystals are still sharp and unabraded the locus of formation 

 can not have been very distant from the present sites. There were 

 probably many sites of crystallization differing in place and time, or 

 we should not see such distinctive characters in the gems from different 

 mines, nor, indeed, in the diamonds from different parts of the same 

 mine. 



THE MECHANISM OF THE DIAMANTIFEROUS PIPES. 



How the great diamond pipes originally came into existence is not 

 difficult to understand in the light of the foregoing facts. They cer- 

 tainly were not burst through in the ordinary manner of volcanic erup- 

 tion. The surrounding and inclosing walls show no signs of igneous 

 action, and are not shattered nor broken even when touching the "blue 

 ground." These pipes after they were pierced were filled from below, 

 and the diamonds formed at some previous epoch too remote to imagine 



