202 THE GENESIS OF THE DIAMOND. 



pressure in the subaqueous volcano, we have the constituents of the 

 diamond in a form admitting of crystallization and the subsequent 

 absorption of its oxygen by the iron always present in its containing 

 walls during long intermittent periods of volcanic inactivity." 



In this presentation Doctor Atherstone dogmatically puts the car- 

 bonic acid gas evolved from the carbonaceous shales into the cavities 

 of the amygdaloid (presumably the melaphyre, which is the only one 

 of the incasing rocks of the volcanic pipes that is amygdaloidal). 

 This gas is then reduced by pressure to a liquid state, in wdiich form, 

 as he thought, the carbon admitted of crystallization. He then ab- 

 sorbed the oxygen of the carbonic acid by the iron in the containing 

 walls of the craters. As the melaphyre existed before the volcanoes 

 burst through it, it is more than probable that the cavities, which ex- 

 isted in it at the time it was erupted, were filled with agate and cal- 

 cite, which they now contain, before the diamond-bearing ground 

 was forced up through it. If the theory above given had any foun- 

 dation in fact, one of two results must have happened, viz, either the 

 resultant diamonds would have been inclosed in tlie amygdaloidal 

 rock or the diamonds must be formed in the " blue " in their perfect 

 state. Both of these assumptions are contrar}^ to facts. As to the 

 derivation of the necessary carbon from the carbonaceous shales sur- 

 rounding the mines, it will be made clear subsequently that this as- 

 sumption is not justified. 



Professor Lewis alleged that the diamond is the result of the in- 

 trusion of igneous rocks into and through the carbonaceous shales. 



He says : " 



Perhaps the most interesting oheiuioal observation concerning the blue ground 

 was that made by Sir H. E. Koscoe. lie found that on treating it with hot 

 water an aromatic hydrocarl)on could be extracted. By digesting the blue 

 ground with ether and allowing the solution to evaporate, this hydrocarbon was 

 separated and found to be crystalline, strongly aromatic, volatile, burning with 

 a smoky flame and melting at 50° C. 



That the rock was a true lava and not a mud or ash is indicated by the fact 

 that the minerals and their associations are those characteristic of eruptive ultra- 

 basic rocks. 



Professor Lewis further says : 



The kimberlite is shared l)y no other terrestrial rock. In structure it re- 

 sembles meteorites of similar composition. If the groundmass of kimberlite 

 were replaced by native iron, it would be nearly allied in both structure and 

 composition with meteorites known as chondrites. 



The "Ava '' meteorite, which fell in Hungary in IS-iQ, contained 

 graphite in cubic crystalline form which Gustav Rose thought was 

 produced by the transformation of diamonds. Later Weinschenk 

 found transparent crystals (diamonds) in the Ava meteorite. Mi- 



1 The Matrix of the Diamond,, Prof. Henry Carvill Lewis, p. 52. 



