320 Dr Pctzliuldt 0)1 the Formation of the Diamond. 



formation of the crystal from the separated carbon during the 

 short continuance of the electrical action of lightning. The 

 formation of a crystal undoubtedly requires infinitely more 

 time than could be afforded during a flash of lightning, and 

 there is not a single instance known of a body crystallizing 

 suddenly during the continuance of an electric spark. 



With regard to the series of opinions according to which 

 the diamond is of vegetable origin, it seems proper to place at 

 their head that of Newton, because, so far as I am aware, it is 

 the oldest, and is at the same time extremely acute. From 

 the great refractive power of the diamond, he concluded it to 

 be a coagulated fatty or unctuous body,* and this idea was 

 started at a time when nothing was known of the chemical 

 constitution, or as to the combustibility of the diamond. This, 

 then, was the first hint of its vegetable origin. Jamesont 

 spoke more decidedly on the vegetable origin of the diamond ; 

 for he expressed the opinion, that it must have been separat- 

 ed, as a form of pm'e carbon, from the sap of some plant, just 

 as silica, in the form of tabasheer, is deposited in the joints of 

 the bamboo and other plants. He adduced, as another proof of 

 his opinion, the remarkable hardness of some woods, as, for 

 example, the Metrosideros vera and others, which he ascribed 

 to carbon approaching the condition of the diamond. Lastly, 

 Brewster adhered to the hypothesis of the vegetable origin of 

 the diamond, and thought he was enabled to conclude, from 

 its polarising properties,^ that it must at one period have been 

 in a soft or pasty condition, but in no degree a product of fire. 

 He further asserted that the former softness of the diamond 

 must have approached most nearly that of hardened gum, and 

 that, like amber, the diamond must have had its origin in the 

 vegetable kingdom, and been the result of decomposition. The 



* Murray's Memoir on the Diamond, p. 13 ; and Froriep's Notixn, vol. 

 xvi. No. 22, March 182?. 



t Jameson's Speculations in regard to the Formation of Opal, Woodstone, 

 and Diamond, in the Memoirs of the "Wernerian Society of Edinburgh, vol. 

 iv. p. 550, and translated in Froriep's Notlzeti, vol. xvi. No. 22. 



\ Quarterly Journal of Science, Oct. 1820. Froriep's Nvtizm, vol. xvi. 

 No. 22. Philosophical Magazine, 3d Series, vol. vii. i). 24!). Poggcndorff, 

 vol. xxxvi. p. 561. Leonhard's Jahrhwh der Mineralogie, 1031, p. 225. 



