38 A CHAPTER ON DIAMONDS. 



similar circumstances, there was a sensible diminution of volume, 

 and also a formation of watery vapour, clearly proving tliat the 

 latter contained hydrogen. Experiment has thus unequivocally 

 demonstrated that the diamond is pure crystallized carbon. 



We have before observed that attempts have been made, both 

 by means of the galvanic battery and the compound gas blow- 

 pipe, to form diamonds artificially, but the attempts have yet met 

 with no greater success than the endeavour to make the Unio 

 Margaritifera, or Meleagriua Margaritifera, form pearls at com- 

 mand. These mollusks either would not obey the commission, 

 or the pearls they did produce were misshapen, unsightly, and 

 worthless. 



The diamond is the hardest of all knovm bodies ; it cuts the 

 i hardest crystals, even rubies and sapphires, and the oriental ame- 

 thyst. Nothing but diamond-powder, obtained by rubbing two 

 diamonds against each other, can polish it ; and it is cut by fi-ag- 

 ments of diamond set in a maule. It requires a temperature of 

 5000 deg. Fahrenheit for its combustion. When exposed to the 

 sunbeam, and carried afterwards into darkness, it exhibits phos- 

 phorescence ; and it is said that such diamonds as do not display 

 this peculiarity, may be made to do so by dipping them into mel- 

 ted borax. It becomes phosphorescent also when fixed to the 

 prime conductor of an electrical machine, and a few sparks are 

 taken from it. The primitive form of the diamond is the octohe- 

 dron; hence its varieties are usually curvilinear polyhedrons, with 

 a lamellar structure, the joints being parallel to the faces of the 

 octohedron. The specific gravity and comparative hardness xaiy 

 but the former is generally estimated at 3500, water being 1000. 



Tradition has always associated the diamond in some mysterious 

 manner with the sun. AYe have seen that it was supposed that it 

 would triumph over all means employed to subdue it, the solar ray 

 excepted. Science has, to a certain extent, corroborated tradition 

 by fusing it with the lens. It becomes, as it were, impregnated 

 wdth an excess of solar light, and carries it as a so-called phospho- 

 rescent body into the dark. Its refractive power exceeds that of 

 any other body. Under an angle of incidence exceeding 24 deg. 

 13 min., it refracts every glimmer of light, which gives rise to its 

 unrivalled brilliancy. It seems, in fact, as if it were an intimate 

 union of a ponderable and an imponderable, and that it embodied 

 in itself the three kingdoms of nature. It is vegetable, by its 



