Platinum was brought to Europe in the middle of the sixteenth century and was soon recognized a true metal, which could not be fused. It remained an expensive curiosity for almost 200 years, until scientists learned its properties, how to melt it in large quantity, and discovered that four new elements, rhodium, iridium, osmium, and palladium, accompanied it (the platinum group metals). The early uses of platinum were in jewelry, laboratory ware, and coin manufacture. By the end of the nineteenth century a platinum-rhodium alloy was adopted for constructing the standard meter and kilogram. Production of platinum grew very slowly; it was only about one ton per year by 1911. The breakthrough came with the discovery of the extraordinary the catalytic properties of the platinum metal group. Today these metals stand at the heart of the petrochemical industry and are the basis of all the means for controlling the emission of obnoxious gases of motor vehicles. Annual production has now reached near 190 tons.