EMERALD 263 



therefore, evident that the carbon found in the beryl did not proceed from the decom- 

 position of a carbonate. 



' Five milligrammes of charcoal treated in the same way, produced a milkiness in 

 all the lime-water bulbs in four minutes. In another experiment, after the usual 

 precautions, 53 milligrammes of graphite were acted on. In four minutes the first 

 bulb, in eight minutes the whole of the bulbs, were rendered milky. 



' The above experiments show, therefore, that the beryl (experiment on one which 

 was from Ireland) contains carbon, not in the state of a carbonate, but in a condition 

 which is more slowly attacked than either free charcoal or graphite ; and it is, I 

 think, probably in the form of diamond, as has been shown to occur with the water 

 contained in artificially-crystallised boron. 



' The presence of carbon in beryls does not appear to be invariable. After repeated 

 experiments upon another large beryl from Haddam County, North America, I was 

 unable to satisfy myself that it contained carbon. It is true there were traces found 

 in the experiment, but they were so minute that they might have been due to organic 

 dust accidentally present. 



' The next point I wished to ascertain was the relation borne by the quantity of 

 carbon in the Irish beryl, to that in the emerald. Minute precautions were necessary, 

 since 1 grm. of the beryl or emerald only yielded 3 milligrammes of carbonic 

 anhydride. 



Experiment 1. Q'9725 grm. beryl gave 0-0030 CO 2 and 0-0131 H 2 



2. 1-0082 0-0031 0-0174 



3. 1-1690 emerald 0-0030 0-0140 

 Expressed per cent. : 



Irish Beryl Emerald Lewy's 



* N Emerald 



I. H. (Mean.) 



Carbonic anhydride . . 0-31 0-31 . . 0-26 . . 0-28 



Water 1-32 173 . . 1-20 ' . ". 1-89.' 



Among the ancients the emerald was very highly esteemed, being ranked by Pliny 

 next to the diamond and pearl. During the middle ages it maintained a very higrh 

 position ; but on the discovery of the Peruvian mines, in the middle of the sixteenth 

 century, it suffered a sudden reduction in value, from which it has never entirely 

 recovered. A stone of 4 grains' weight is said to be worth from 4. to 51. ; one of 

 8 grains, Wl. ; one of 15 grains, being fine, is worth 601. ; one of 24 grains fetched, at 

 the sale of M. de Drue's cabinet, 2,400 francs, or nearly 100. 



From the descriptions of the smaragdos, or emerald of the ancients, it is evident 

 that they confounded under this name a number of green minerals differing widely 

 from each other in general characters ; such, for example, as malachite, chrysoprase, 

 green fluor-spar, amazon-stone, and even green glass. The true emeralds of the 

 ancients were probably in great part derived from Mount Zabara, in Upper Egypt, 

 where the old workings were discovered some years back by the French traveller 

 M. Cailloud, and were re-opened by Mohammed Ali ; but the emeralds obtained being 

 only of poor quality, the operations were soon suspended. 



For many years past, the emerald has been obtained almost exclusively from the 

 famous mine of Muzo, a large open excavation on the eastern cordillera of the Andes, 

 75 miles N.N.W. of Santa Fe de Bogota. It there occurs, associated with crystals of 

 iron pyrites and the rare mineral parasite, in veins of calcareous spar traversing a 

 black bituminous limestone, containing ammonites and other fossils, apparently of 

 lower cretaceous age. When first removed from the rock, the emeralds are excessively 

 fragile ; and numbers of them crack spontaneously, in spite of careful protection from 

 the sun. The emeralds are indeed so rarely free from flaws that they are often imitated 

 in fictitious gems. 



The Muzo mines were leased, in 1864, to a French Company, in consideration of an 

 annual payment to the Government of Columbia of about 3,000^. The workings are con- 

 ducted under the direction of M. Lehmann, and the emeralds which are obtained are 

 sent direct to Paris. The present agreement expires this year 1874 and it is under- 

 stood that it will not be renewed. 



A fine crystal of Muzo emerald, 2 inches long, exhibited in the Great Exhibition of 

 1851, is now in the cabinet of the Duke of Devonshire ; it measures across its three 

 diameters 2| in., 2| in. l|in., and weighs 8 oz. 18 dwts. : owing to flaws, it is but par- 

 tially fit for jewellery. 



Emeralds of less beauty, but larger than the South American gems, occur in Siberia. 

 One specimen in the Imperial Eussian collection measures 14^ inches long and 12 

 broad, and weighs 16| Ibs. troy; another is 7 inches long and 4 inches broad, and 

 weighs 6 Ibs. troy. The Siberian emerald occurs near Ekaterinburg, embedded in 



