Third Method of Artificial Production of Precious Stones

M. Daubree had pointed out in 1841 the principle upon which, in 1849, he produced artificially a certain number of crystallized minerals. The idea was to compel the vapour of water to react at a certain temperature upon the metallic fluorides, chlorides, &c., themselves brought to the state of vapour by the action of heat.

In these conditions a double decomposition is produced, and metallic oxides are formed, which crystallize.

Results of the same order are produced by introducing only the vapours of the metallic combinations destined to give rise to new bodies.

M. Daubree obtained by this process a great number of species perfectly crystallized; among them the oxide of tin and quartz. Instead of making the vapours react upon each other, he made them react upon solids, and the results were no less satisfactory. It is by the employment of this method that M. Daubree has produced first the apatite, and a compound having a close analogy to the topaz; and more lately has, by the use of the chlorides of silicon and aluminium, produced crystallized silicates and aluminates.

M. Durocher has obtained a great number of crystals by a method similar to that of M. Daubree. The only essential differences between their processes is that Durocher used soluble combinations which pertained each one to the elements of the mineral he wished to crystallize, and Daubree interposed vapours of water as a means of decomposing the generating vapours.

The latest experiments in the reproduction of crystals, and particularly of precious stones, have been made by MM. Deville and Caron. The method employed by these chemists is founded upon the same principle as those of Daubree and Durocher; but the agencies employed by them are incomparably more powerful, and the results which they have obtained more brilliant.

With the enormous temperature developed by the furnaces of Deville and Caron ordinary crucibles could not be used: they melted like lead. The crucibles which they used were made of lime. Anybody can make them, and they are absolutely fireproof.

Among the principal results obtained by the experiments of these chemists were crystals of white corundum, rubies, and sapphires.

The crystals of corundum, nearly two-fifths of an inch in length, exhibited all the crystallographic and optical properties of the natural corundum. The rubies, obtained very nearly in the same way, had the violet-red tint of the natural ruby conveyed to them by the oxide of chromium, which furnished also, in a different proportion, the blue of the sapphires. Sometimes, in the experiments of Deville and Caron, red rubies and sapphires of the most beautiful blue were obtained side by side.

A similar experiment produced specimens of cymophane identical in all respects with the cymophane found in America, in small but very perfectly formed crystals.