The earliest practical use of chemical processes was by metal smiths of the ancient world. These artisans learned how to use heat to melt various naturally occurring metals together to form alloys such as bronze. Early manufacturers of cloth also used primitive chemical processes to set dyes. In the following centuries, chemical processes were studied through the pseudo-science of alchemy, which attempted to change base metals into gold. Although alchemists were, of course, unsuccessful, they did develop many valuable chemical processes as a result. The manuscripts produced by alchemists were studied by succeeding generations, and an effective knowledge of chemistry had been accumulated by the late 13th century. In the 17th century, the ideas of alchemy finally died out as an increasing body of true chemical knowledge was gained through experimental analysis, leading to the modern science of chemistry.