14 Anniversary Address. 



As an item in this enquiry, we may refer to a notice in 

 Sillimari's American Journal (VI., llO), 1848, by Professors 

 E. and W. B. Rogers, referring to a previous paper, on " A new 

 method of determining the carbon in graphite," (V., 392,) in 

 which the authors show, that " the DJamond may be converted 

 into carbonic acid in the liquid way, and at a moderate heat, by 

 the re-action of a mixture of bi-chromate of potassa and 

 sulphuric acid, in other words, by the oxydating power of 

 chromic acid." The method is much the same, as in the process 

 of oxydating graphite. By this method, they obtained from 

 half a grain of Diamond, an evolution of as much carbon as was 

 nearly equal to what was due to the entire weight of the 

 Diamond. 



On the other hand, Sir J. Herschel (Physical Greography) 



quotes the case of a Bahia Diamond mentioned by Harting, 



which contained well-formed filaments of iron pyrites, and he 



infers from the combination of iron and carbon at high 



'temperatures the possibility of an igneous origin for Diamond. 



A paper by Messrs. Sorby and Baker was read in 1869, before 

 the Boyal Society of London, on the structure of certain 

 minei'als, among them Euby, Sapphire, and Diamond, showing 

 that these gems contain cavities entirely or partially filled with a 

 liquid, probably condensed carbonic acid, as well as with 

 crystals — that some Emeralds contain a strong saline solution 

 with cubic crystals, probably of chloride of potassium, and that 

 the black specks in Diamonds (such e. </., as those seen in our 

 Cudgegoug mineral) are really crystals, which are sometimes 

 surrounded by contraction cracks, a black cross appearing under 

 polarized light. The authors conclude, that the Diamond does 

 not aff"ord positive evidence of a high temperature, though not 

 opposed to it. 



That its structure has great peculiarities has been shown by 

 the changes produced in a yellow Diamond by heat. This stone 

 was exhibited by M. Eremy to the Academie des Sciences at 

 Paris in 186G, when it w^as seen to become rose-coloured by the 

 application of heat, returning to its proper tint on cooling. It 

 is said to be the first instance of such a phenomenon. But, on 

 turning to the 7th Eeport of the British Association, it will be 



