I860.] on Diamonds, 231 



In the diamond, splinters of ferruginous quartz have been found. A 

 high antiquity and an origin perhaps contemporaneous, and not 

 improbably connected with the geological distribution of gold in quartz 

 veins, may be inferred from these facts. 



The chemist has to deal with a more general problem ; that of the 

 methods, whether employed by nature, or open to his own ingenuity, 

 for producing the diamond. Many solutions for this problem have 

 been and may be proposed : — 



1. The authority of Liebig supports the view of a process of 

 eremacausis having converted organic compounds into diamonds. 



2. The decomposition of binary carbon compounds by replace- 

 ment of the carbon by some other elements. 



3. A process of sublimation. 



4. Cooling from fusion under pressure (supposing carbon other- 

 wise to vaporise without fusion, like arsenic). 



5. Deposits from voltaic currents between carbon poles. 



6. Deposits on the cooling of fused metals (or other substances ?), 

 surcharged with carbon. 



7. The separation of carbon from carbonates, analogous to that 

 of silicon from silicates, which may be effected by magnesium at a 

 red heat, and by lithium far under red heat. 



And these do not exhaust the number of possible suggestions. Of them, 

 one (the 6th) possesses peculiar interest. 



Graphitic boron and silicon are formed by the cooling of fused 

 aluminium, surcharged with these elements ; and the same elements — 

 in other respeqts so closely grouped with carbon — separate in the 

 adamantine form from zinc,^under analogous circumstances. The latter 

 are crystallised indeed in different systems from diamond, but they 

 possess many of its characters in a remarkable degree. 



Mr. Maskelyne then adverted to some* of the largest diamonds 

 that have been recorded, and concluded with a few facts regarding 

 the Koh-i-Nur. These had chiefly for their object, to prove that the 

 great diamond of India, which the Emperor Baber records as having 

 been taken at Agra, by Humayun, in May 1526, was the Koh-i- 

 Nur, now the crown jewel of England. This was based on the 

 identity of weight of the diamond (before it was cut) in 1851, with 

 the eight mishkals, which Baber declared to have been its estimated 

 weight. It is difficult to state, precisely, what the mishkal was in 

 Baber's day. His coins and Humayun's are very scarce ; but even in 

 their greatly worn state, these early Mogul silver coins, or dirhams, 

 average above 71, and range up to 71*5 grains, probably correspond- 

 ing to a coined value of at least 73, and perhaps even 74 grains. 

 These probably represent the mishkal. It is not less difficult to 

 determine what was the precise weight of the Bokhara goldsmith's 

 mishkal, which would have been the basis of Baber's coinage, in the 

 16th century ; but among the old Samanian coins (of Bokhara and 

 Samarkand, a.d. 961 — 1165) are some from which it would seem, 

 that besides the old dinar, of about 66 grains, and a dirham, of 50, 



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