Synthetic Chemistry - - - Ultramarine.

Scientific American 16, 3.1.1852

There are two very distinctive processes in chemistry, viz., analytic and synthetic; the former takes a quantity of matter and resolves it into its original elements; the latter takes those original elements, combines them together and makes up the resolved quantity of mater into its first form and quality in every sense. It may be supposed by many that if a chemist can resolve any wuantity of mater to its original elements - analyse it - he can easily combine them by synthetical chemistry. This has been done in many instances and with many compounds. Water can be thus treated but many substances elude the genius and skill of the chemist to treat synthetically. The laws of synthetical chemistry are not so well understood as those of analysis, and perhaps never will.

In no single instance has chemistry witnessed a greater triumpg of synthetic skill, than in the formation of lapis lazuli. This mineral had been known and used by ancient artists away back in the days of Egyptian and Grecian glory, and it had come down as the most beautiful azure color ever discovered. It remained unchanged by exposure to air or fire, and it maintained its sky blue brilliancy on the canvas, undimmed for centuries. This mineral was very dear, and previous to 1820, it was all obtained in China and Siberia. At the time mentioned, common ultramarine sold for 30 dollars per ounce, and the best quantity for upwards of $100 per ounce. This substance was analyzed and was found to be a compound of silica, alumina, sulphur, and soda, with a trace of iron. These were colorless substances, and for a long time the coloring principle eluded the grasp of the chemist. At last M. Guimet, a chemist of Lyons, France, devoted his attention exclusively to try and make artificial lapis lazuli - ultramarine. He was encouraged by the offer of a reward of 6,000 francs by the Society of Encouragement in Paris. He gave up the idea of searching for a hidden coloring principle and tried experiments with colorless substances. He succeeded, and for a long time kept his secret, and sold his ultramarine at $11 per pound. The process was afterward discovered by ther chemists in Paris, (Gmelin and Robiquet) who published the mode of making it. This beautiful pigment is now sold as low as a few dollars per pound, and a quality as good as the second quality of the old lapis lazuli, which sold for $35 per ounce, can now be purchased for a few shillings per pound. Mr. Guimet was an exhibitor at the Great Exhibition and was awarded a Council Medal for his useful discovery. He states that it may be made by rapidly igniting a mixture of equal parts of silica, carbonate of soda, and sulphur, adding a sufficient quantity of the solution of soda to dissolve the silica. The result of this is a bluish green mass, which when burned in the air becomes the beautiful azure ultramarine.

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