Diamonds* 



By H. J. LoGiE 2 



Professor of Experimental Physics 

 University of the Wilwatersrand 



I HAVE clioseii in this inaugural lecture to talk about the diamond ; 

 it is the hardest known natural mineral; it cannot be scratched by 

 anything but another diamond ; it cannot be dissolved by any known 

 liquid or melted by any conventional tecliniques. From the scien- 

 tific point of view it is the prototype of crystals which show covalent 

 bonding and from this viewpoint alone it is of great interest, since 

 the whole crystal can be looked on as one giant molecule. 



Much of the wealth of South Africa has come from gold and from 

 diamonds, and yet it is remarkable how little research has been done 

 in this comitry into the fmidamental properties of either. In the 

 case of diamonds, the Diamond Research Laboratories in Johannes- 

 burg are a notable exception and it was largely through financial help 

 from them that a program of diamond research was instituted at this 

 university. It is some of the results of these studies which will be 

 presented in this lecture. However, though the ordered inner struc- 

 ture of the diamond is the chief concern of the scientist and of this 

 lecture, even the scientist cannot be completely indifferent to the out- 

 ward beauty of the gem nor can he fail to be intrigued by the part 

 which diamonds have played in the history of this country, and by 

 the stories which have grown up around some of them. I would not 

 be doing full justice to the subject if these aspects were completely 

 ignored. 



With complete lack of scientific foundation, the diamond has been 

 credited with many marvelous virtues ; amongst others the power of 

 averting insanity and of being an antidote to poison; and in the 

 Middle Ages it was known as the pietra della reconciliazione — as the 

 peacemaker between husband and wife. I understand that a belief 

 in this property is not without its adherents today. The diamond, 



^ Inaugural lecture delivered May 21, 1958, at the University of the Wltwatersrand. Re- 

 printed by permission of the Wltwatersrand University Press, Johannesburg, South Africa, 

 publishers. 



* Professor Logle died Nov. 8, 1958. 



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