Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/69

 following experiment is worthy of being recorded. A small portion of iron was put into a crucible with a fragment of a Diamond, and exposed to a strong heat; on examination the iron was found to be converted into steel.

of bad color are often improved by being exposed to a certain degree of heat in a small crucible, or the bowl of a tobacco-pipe, surrounded in some instances with borax. It is necessary for the vessel to be closely filled with charcoal, to prevent the admission of air.

Diamond possesses double refraction; which is rather difficult to discover., By friction it becomes electric, but continues so only a few minutes.