IMiKi Inl'S .sTO.NKS. 



04:5 



ceons shale; that from information he had re- 

 ceived from New .South Wales, Borneo, and 

 IJra/.il, he believed that all diamonds were i In- 

 n-Mi It of the intrusion of a peridotite through 

 carbonaceous rooks and coral .-i-nm~. 



Artificial Diamond. In ISHU Mr. J. Bullan- 

 tine llannay claimed to havo produced artificial 

 diamonds by tightly sealing in steel and irn 

 tubes or coils about 4 inches thick, made by bor- 

 ing out a solid block of iron, a mixture of 10 

 per cent, of bone oil and 90 per cent, paraflin 

 spirit, and subjecting these tubes to intense heat 

 for some hours. After 80 experiments he ob- 

 tained 14 milligrammes of residue, part of which 

 he called diamond. The substance was pro- 

 nounced diamond by Profs. Maskelyne, Roscoe, 

 Stokes, and others. In 1888 C. A. Parsons made 

 a series of experiments on carbon at high tem- 

 peratures and under great pressure, and with 

 other substances for the purpose of producing a 

 dense form of carbon for use in arc and incan- 

 descent lamps. The results proved unsatisfac- 

 tory, but incidentally there was obtained on the 

 surface of the carbon rod a gray powder harder 

 than emery and capable of scratching the dia- 

 mond, which he concluded was probably dia- 

 mond itself. A full account of the experiments 

 was given in a paper read before the Royal 

 Society of London. 



Ruby. The Burmese ruby mines have cost 

 the British Government a vast sum of money. 

 During the wars of 1826 and 1852 England ex- 

 pended $75,000,000 and $15,000,000 respectively, 

 and after this sacrifice the Burmah and Bom- 

 bay Trading Company claimed that King The- 

 baw of Burmah had arbitrarily canceled the 

 leases by which the company controlled the out- 

 put of the ruby mines near Mandalay. The war 

 of 1886 followed and involved the raising of an 

 army of 30,000 men and an outlay of $5,000,000, 

 but the British Government gained control of 

 the ruby mines. They are in the valley of the 

 Mogok, about 75 miles north of Mandalay, at an 

 altitude of 4.200 feet. Concerning them very 

 little was known, as they were always the monop- 

 oly of the Crown and were jealously guarded. 

 It was said that they paid King Thebaw's Gov- 

 ernment 100,000 rupees annually, and in one 

 vear 150,000 rupees. Mining is carried on there 

 by about 50 wealthy natives, who employ the 

 poorer townspeople at liberal wages. All the 

 gems are sent to Ruby Hall, Mandalay, to be 

 valued. 



Artificial Rnby. This subject is of import- 

 ance not only commercially, but as illustrating 

 the surprises that chemistry is constantly giving 

 us. In 1886 the syndicate of dealers in precious 

 stones in Paris were informed that certain 

 stones, put upon the market by a Geneva house 

 and sold as rubies from a new locality, were 

 suspected to be artificial. It was surmised that 

 they were obtained by the fusion of large num- 

 bers of small rubies, worth a few dollars a carat, 

 into one fine gem valued at from $1,000 to 

 $2,500 a carat. Some of these artificial stones 

 were examined by George F. Kunz, who found 

 that the principal distinguishing characteristic! 

 between them and genuine stones was the pres- 

 ence of spherical bubbles, with rounded ends, 

 similar to those seen in glass or other fused 

 mixtures. When examined individually they 



seemed to be filled with gas or air that often 

 formed pajt of a cloud, the rest having the 

 wavincss of a fused mixture. A few were ob- 

 served inclosing inner bubbles, apparently a 

 double cavity, out empty. In natural rubies 

 the cavities are angular or crystalline in outline, 

 and are usually filled with some liquid, or if 

 they form part of a " feather," as it is called by 

 the jewelers, they are often arranged with the 

 lines of growth. Hence the difference in ap- 

 pearance between the cavities in the natural gem 

 and those in the fused gem is very distinct, and 

 can readily be detected by means of a pocket 

 lens. No traces of anything like a crystalline or 

 angular cavity were found in any of the artificial 

 stones, and in many genuine rubies there is a 

 flossv-Iooking structure, called "silk" by the 

 jewelers, which, if examined under the micro- 

 scope, is found to be a series of cuneiform or 

 acicular, often iridescent, crystals, arranged 

 parallel to the hexagonal layers. When in suf- 

 ficient number these crystals produce the asteria 

 or star effect common to the gem when cut '"en 

 cabochon," as the carbuncle or convex cut is 

 called, with the center of the hexagonal prism on 

 the top of the cabochon. This condition is ab- 

 sent from the artificial stones, as well as the 

 marking of the hexagonal crystal, which can 

 often be seen when the light is allowed to strike 

 obliquely across the hexagonal prism. These 

 artificial rubies were probably produced by a 

 process similar to that described by Edmond 

 Fremy and Feil in 1877. An aluminate of lead 

 is used with silica in a siliceous crucible, the 

 silica unites with the lead to form a lead glass, 

 and the alumina crystallizes out in the form of 

 corundum in hexagonal plates, with a specific 

 gravity of 4'0 to 4 - l, and the hardness and color 

 of the natural ruby, the latter being produced by 

 the addition of some chromium salt. By this 

 method rubies were formed that, like the true 

 gem, decolorized temporarily on heating. Gau- 

 din's method for producing artificial gems con- 

 sists in exposing amorphous alumina to the 

 flame of the oxyhydrogen blowpipe, fusing it to 

 a limpid fluid, which, when cooled, had the 

 hardness of corundum, but the specific gravity 

 only of 3'45. The French syndicate referred the 

 matter to M. Friedel, of the School of Mines, 

 Paris, and supplied him with samples of the 

 stones for examination. He reported the pres- 

 ence of the round and pear-shaped bubbles and 

 determined the hardness and specific gravity to 

 be about the same as in the true ruby. The 

 syndicate then decided that all cabochon or cut 

 stones of this kind should be sold as artificial 

 and not as precious gems. Unless consignments 

 were so marked, the sales were to be considered 

 fraudulent and the misdemeanor punishable 

 under the penal code. All the sales that had 

 been effected, amounting to 600.000 or 800,000 

 francs, were canceled, and the money and the 

 stones were returned to their owners. Edmond 

 Fremy has published the successful result of a 

 second series of experiments to produce artificial 

 rubies. By the former process the rubies ob- 

 tained were defective, but by the new process 

 perfect rubies 1 to 2 millimetres in size were 

 produced, having the purity of the natural pern 

 and scratching topaz. His method is to fuse 

 fluoride of borax and aluminum containing bi- 



