The Orientals, taking advantage of the facility with which the prisms are broken at right angles to the axis, frequently used slices of the crystals, sometimes artificially polished, but often with the natural planes of cleavage preserved. This practice was quite common prior to the fifteenth century. They also adopted the unfortunate custom of engraving them with condensed quotations from the Koran, and often drilled holes through the centre of the stones so as to string them as necklaces or as ear ornaments. One of the finest gems that adorned the gorgeous harness of Runjeet Singh was a beautiful emerald maltreated in this manner. Major Pearse found in a Punjaub tope a reliquary formed from an emerald three inches long and two inches thick, with the ends rounded off. It was originally a gem of fine color, but had been bored half through its axis to contain two finger joints of some revered Buddhist saint or petted monkey. The emerald has been a subject of controversy among the chemists and mineralogists, and its character, especially the cause of its beautiful color, is not clearly defined even at the present day. But that distinguished chemist, Professor Lewy of Paris, seems to offer, thus far, the most correct and plausible theory. More than ten years ago he boldly asserted that the hue is not due to the oxide of chromium, and with this opinion he confronted such eminent men as Vauquelin, Klaproth, and others of high rank in the scientific world. Not content with his researches in his laboratory in Paris, he resolutely crossed the ocean and sought the emerald in its parent ledges in the lofty table-lands of New Granada. Here he obtained new information of a geological character which goes far to strengthen his position. The experiments of M. Lewy indicate, if they do not prove, that the coloring matter of the emerald is organic, and readily destroyed by heat, which would not be the case if it was due to the oxide of chromium. All my own fire-tests with the Granada emerald corroborate the views of M. Lewy, for in every instance the gem lost its hue when submitted to a red heat. Nevertheless, the recent researches of Wöhler and Rose give negative results. These experienced chemists kept an emerald at the temperature of melted copper for an hour, and found that, although the stone had become opaque, the color was not affected. They therefore considered the oxide of chromium to be the coloring agent, without, however, denying the presence of organic matter. The amount of the oxide of chromium found by many chemists varies from one to two per cent, while Lewy and others found it in a quantity so small as to be inappreciable, and too minute to be weighed. Before the ordinary blowpipe the emerald passes rapidly into a whitish vesicular glass, and with borax it forms a fine green glass, while its sub-species, the beryl, changes into a colorless bead; with salt of phosphorus it slowly dissolves, leaving a silicious skeleton.