This seems to have been an actual invention, in that it followed a discovery made by Wedgwood that sunlight acted on nitrate of silver, and was the embodiment of an idea, then conceived by him, to utilize his discovery in making profile pictures. His invention was far from perfect, however; the greatest imperfection being the fact that the pictures could not be fixed; because, unless the paper was ever afterward kept away from the light, its whole surface would become dark, and the picture therefore cease to exist. In consequence, it aroused almost no interest whatever at the time. In 1814, M. Niepce invented a process that he called "heliography," by which he made pictures on silvered copper covered with a thin solution of asphaltum. In 1829, Daguerre and Niepce entered into a copartnership for developing heliography, and instituted experiments that led Daguerre to inventing the daguerreotype, made by a process quite new in detail, but based on the earlier inventions of both Wedgwood and Niepce. The daguerreotype was followed in 1850 by the present "photograph." The invention of electroplating was made by Brugnatelli in Italy in 1803. The fact that electric currents could decompose certain liquids had been known since 1800, and also the further fact that oxygen and hydrogen, acids and alkalies, appeared at the positive and negative poles respectively of the wires in contact with the liquid. But Brugnatelli seems to have been the first to conceive the idea of utilizing these facts in a device whereby he could deposit metals at will at the negative end of a solution. In the embodiment of his conception, pieces (say of silver) were hung on rods in connection with the positive pole of the battery supplying the electric current, while the articles to be plated with silver were hung on rods connected with the negative pole. The value of this invention and its extensive use in the electrodeposition of metals at the present day are well known. In the following year, Sir Humphry Davy, working along the general line of electrical decomposition of liquids, made a number of super-brilliant investigations. Possibly the most important result was his discovery of a new metal, to which he gave the name Potassium, formed at the negative pole by the electrical decomposition of moistened caustic potash. He followed this by decomposing caustic soda and discovering another new metal, that he named Sodium.