The same may be said of the other metals, their properties not being much known. _Molybdenum_ was first procured in a metallic state by Hielm, in the year 1782; and, it is believed, has been employed in some processes of dyeing in Germany. As the ore may be had in great plenty, it will probably, some time hence, come into general use here. At present it is not used in any of the arts. Its specific gravity is 8.61. _Uranium_ was discovered by Klaproth in 1789, in a mineral called pechblend; and has since been found combined with carbonic acid, in the common green mica. _Titanium_ was first noticed in the year 1781, by Mr. Macgregor, in a greyish black sand, found in the vale of Menachan in Cornwall; but has since been discovered by Klaproth in several other minerals. An ore of it occurs in Transylvania, which very much resembles yellow sand. This metal has been used in France for painting porcelain. _Tellurium_ was discovered by Klaproth in the year 1798, in a particular kind of gold ore. It has hitherto been found in quantities too small to allow of its being employed in the arts. Its specific gravity is only 6.115. _Chromium_ received its name from a property it has of imparting a lively color to a variety of other bodies. The emerald is colored by an oxide of this metal. _Columbium_ was discovered in a mineral sent from Massachusetts in North America. _Tantalium_ was found in an ore from Swedish Lapland: but Dr. Woollaston has lately discovered that this and columbium are identically the same metal. _Cerium_ had not been seen in a metallic form till Sir Humphrey Davy procured it from some oxide discovered by Hissinger and Berzelius in 1804. Its scarcity will prevent its being applied to any useful purpose. The metals are simple substances, distinguishable from all other bodies by their lustre, great specific gravity, perfect opacity, and superior power of conducting electricity. They are the great agents by which we are enabled to explore the bowels of the earth, and examine the recesses of nature. Their uses are so multiplied, that they are become of prime importance in every occupation of life. The reason why one metal possesses such opposite and specific differences from those of another, is not to be attributed to chance, but must certainly be the effect of consummate wisdom and contrivance. These metals differ so much from each other in their degrees of hardness, lustre, color, elasticity, fusibility, weight, malleability, ductility, and tenacity, that the Author of nature appears to have had in view all the necessities of man coming within the range of their operation.[112] [It is now generally admitted that there are FORTY _distinct metals_.