NATURE OF THE DIAMOND. 149 



plained by the theory of crystallization, for which we are indebted 

 to the sagacity of Mr. Hauy ; a theory which, for its ingenuity, 

 clearness, and importance, must ever rank high, and which must 

 be considered as one of the greatest acquisitions which mineralo- 

 gy, and even chemistry, have hitherto attained. 



According to this theory, the additional matter which envelopes 

 the primitive nucleus consists of thin slices or layers of particles 

 laid one above another upon the faces of that nucleus, and each 

 layer decreasing in size, in consequence of the abstraction of one 

 or more rows of integrant particles from its edges or angles. 



[Thomson. 





CHAP. XL 



ON THE NATURE OP THE DIAMOND. 



J. HE diamond is not more an object of attention to the jeweller 

 or lapidary than to the chemist ; for it is as singular in its compo- 

 sition among the crystals, as it is valuable, on account of its rarity 

 and lustre, among the gems : having of late been fully ascertained 

 to consist of nothing more than pure charcoal under a peculiar 

 state of crystallization. 



Upon this subject we shall copy Mr. Smithson Tenant's interest, 

 ing paper, as communicated to the Royal Society in 1797. 



Sir Isaac Newton having observed that inflammable bodies had 

 a greater refraction, in proportion to their density, than other 

 bodies, and that the diamond resembled them in this property, 

 was induced to conjecture that the diamond itself was of an in. 

 flammable nature. The inflammable substances which he employ, 

 ed were camphire, oil of turpentine, oil of olives, and amber; 

 these he called "fat, sulphureous, unctuous bodies;" and using 

 the same expression respecting the diamond, he says, it is pro- 

 bably " an unctuous body coagulated." This remarkable conjec- 

 ture of Sir Isaac Newton has been since confirmed by repeated 

 experiments. It was found, that though the diamond was capable 

 of resisting the effects of a violent heat when the air was carefully 

 excluded, yet that on being exposed to the action of heat and air, 

 it might be entirely consumed. But as the sole object of these 



fcj 



