Mat S, 18S5.] 



• KNOWLEDGE 



391 



»t a red heat for several hours. Out of eighty exi)eri- 

 ments only three were successful, the great pressure exerted 

 by tl»e confined gases frequently bursting the tubes ; while 

 another source of disappointment lay in the fact that many 

 of the iron tubes proved to be quitt: porous when red hot, 

 so letting the gases escape. When everything went on 

 properly the boneoil was decomposed, its hydrogen being 

 attracted by the lithium, while the carbon was deposited 

 on the bottom of the tube as a black mass containing 

 microscopic diamonds. Although the cost of the diamonds 

 produced In this manner was many times greater than the 

 sum for which they could have been obtained at a jeweller's, 

 yet the result was of the highest theoretical interest and 

 importance. 



DIAMAXTIFEROUS LOCALITIES. 



"Cp to about two centuries ago, India was the principal, 

 if not the only known home of the diamond. The diamond 

 mines occur in the Deccan, an elevated tableland in the 

 southern part of India, the gems being found in a coarse 

 gravel which is probably derived from sandstone-rocks 

 belonging to the Lower Silurian formation. Golconda, 

 so frequently referred to as the home of the diamond, never 

 produced any diamonds at all, being merely the mart to 

 which the diamonds were brought to be sold. When India 

 was governed exclusively by native princes, who disposed 

 of the labour of tlieir subjects as they thought fit, the 

 digging and washing of the diamond - gravels of the 

 Deccan yielded a large number of the precious stones. 

 Now that the Hindoo labourer requires a suitable wage, and 

 is protected from oppression by the British Government, 

 the search for diamonds in India is found " not to pay." Of 

 all the precious stones found in India, the Koh-i-noor is, 

 perhaps, the best known to us, because it now occupies the 

 place of pride among the jewels belonging to the Crown. 

 It is believed to have been found in the mines at Kollur, 

 and its original weight was 790 carats. When the traveller 

 Tavernier saw it in the possession of the Great Mogul 

 (Aurungzebe), in 1665, it weighed only 280 carats, and it 

 is believed that the cutter (Borgio, a Venetian), to whom 

 it was entrusted, detached by cleavage more than one 

 fragment, which he converted to his own use. After 

 several vicissitudes, this "Mountain of Light" was con- 

 fiscated by the East India Company in 18.50, and presented 

 to the Queen. Its weight was then 186 carats, but the 

 recutting, by Coster of Amsterdam, further reduced it to 

 106 carats. Owing to the unskilful way in which this fine 

 ^em has been treated, its lustre is still unsatisfactory. 



The diamonds of Brazil were discovered early in the 

 eighteenth century in the province of !Minas Geraes. They 

 were obtained from the cascalho, a coarse gravel produced 

 by the decay of a quartzite or hardened sandstone. To this 

 sandstone itself the name of itacolumite has been given, and 

 diamonds have been found in the solid rock. But as we 

 know sandstones to be formed Vjy the wearing away of 

 older rocks, it is uncertain whether the diamonds have 

 been produced in the itacolumite, where we now find 

 them, or whether they are there simply as natural ingre- 

 •dients of the rock, like the grains of sand of which it is 

 mainly composed. 



Between the years 1772 and 1818 diamonds to the 

 weight of three million carats, and worth £7,000,000, were 

 exported from Brazil. But as the deposits began to be 

 worked out, the produce was far less, and the value of the 

 stones exported between 18C1 and 18G7 was under two 

 millions sterling. Since the latter date, the Cape diamonds 

 have caused a still greater reduction in the extent and 

 value of the Brazilian mines. The Brazilian diamonds are 

 mostly small, the largest known, the " Star of the South," 

 weighing 254 carats, which was reduced to 124 carats after 



cutting and polishing. Besides dazzling brilliants, the 

 mines of Brazil have yielu'd an impure black form of 

 crystalline carbon, called carbonado, which occurs in lumps 

 sometimes 2 lb. in weight. These black diamonds are now 

 much used in boring operations, being sit at the end of a 

 crown or cylinder of steel, which is made to revolve rapidly 

 by steam-power, \^y this means haul rocks are penetrated 

 with comparative ease, and borings to depths of from one 

 thousand to two thousand feet have been executed at a 

 greatly reduced cost, and in a less space of time than 

 previously. 



Of other localities from which diamonds have been ob- 

 tained we can here only lirielly allude to Australia, where 

 large numbers of small stones have been found since 1852 

 in the alluvial deposits from which so much gold has been 

 washed ; the Ural ^Mountains, where the |)recious stones 

 are associated with gold and platinum ; and Jiorneo, where 

 the Rajah of ^M^ttam is said to possess a diamond weighing 

 367 carats. The diartond-Uelds of Isoulh Africa, which 

 have thrown all the other " diggings " completely into the 

 shade, we shall now proceed to describe with more detail. 

 Before leaving the other diamantiferous regions we may, 

 however, note that the diamonds they yield ap)icar almost 

 invariably to occur in gravels deri\ed from ancient and 

 metamorphosed rocks, and that gold — deiived from the 

 same .source — almost invariably accompanies the gems. The 

 seeker for rough diamonds must divest himself of the idea 

 that they possess the sparkle and brilliancy of the cut and 

 polished gems ; the fact is, that they mostly look like bits 

 of hardened gum ! 



{To he continued.) 



GEORGE ELIOT ON OLD AGE. 



IN the New York Tribune, Mr. Robert Buchanan pub- 

 lishes an interesting account of a conversation with 

 George Eliot and Mr. Lewes. In the course of this con- 

 versation, the subject of old age was raised, and the 

 following suggestive remarks were interchanged : — 



George Eliot — Queyn Di diligunt, &.C. After all is not 

 Ganymede to be envied 1 Better to be snatched up sud- 

 denly into the heaven of heavens, in all the prime of youth 

 and happiness, than to grow old in a world which is full of 

 sorrow, and in which old age is the least beautiful of human 

 phenomena. 



Lewes — You are quite right there. It is the exaggera- 

 tion of sentiment which makes the poets give old age a 

 sort of moral halo. There is nothing so pitiful, so hor- 

 rible, as the slow and certain decay of the human 

 faculties. 



Buchanan — But is not that decay beautiful too 1 



Lewes — Apart from the jiathetic fallacy, as Ruskin 

 calls it, not at all. Your favourite Catullus describes it 



perfectly : — 



Cana tempus anilitas 

 Omnia omnes annuit ! 



In other words and Scotch ones, " a' nodding, nidnid- 

 nodding;" a condition, in shot t, of ever-increasing imbe- 

 cility, or vacuity. 



George Eliot (smiling)— We are wandering toward deep 

 waters. But it is quite true, I think, that the gradual 

 obliteration of the human faculties and senses, one by one, 

 is the strongest argument against the popular conception 

 of a personal immortality. 



Lewes — Certainly. 



George Eliot — Not only do men, under circumstances of 

 physical decay, become feeble and imbecile ; when a moral 

 sense remains, it frequently becomes perverted. I have 

 seen an old gentleman, hitherto known as an immaculate 



