104 



discovered just at the spot where the diamond should have 

 been, but not a vestige of the precious stone remained. 



The only explanation of its departure that seems feasible 

 is, that the soda carbonate, causticised by the lime hydrate, 

 had by its affinity for carbonic acid assisted the oxygen of 

 the atmosphere getting through cracks in the clay, to 

 oxidise the pure carbon of which the diamond is composed 

 at a vastly lower temperature tlian would in ordinary 

 circumstances have been required — at all events this gem 

 was entirely volatilised at a very low red heat. 



