is of a smoky colour. A diamond which is perfectly symmetrical, sharp-edged, lustrous, big, and without a stain is called a Purusha or a male diamond. It is considered the best as far as its medicinal use goes ; it restores vigour and can be prescribed to all with advantage. That which exhibits stains and cracks, and which is hexangular, is distinguished as a female diamond, and its bhasma is beneficial to females only. Diamonds that are long and triangular are neuter and are considered powerless.
But of all the minerals Mercury is recognised as the most important by the Indian physicians. Marvellous powers are attributed to it. It was no doubt known to the Romans and Arabs who employed it externally, but the Hindoos seem to be the only people who prescribed it internally. It is found in many parts of India, and was known to its people from a very early date. Being a volatile substance it is unmanageable for purification and 'killing' without a good deal of care and patience. But if once brought under subjection, it proves, say the Hindoos, an in- valuable medicine for curing some of the most obstinate diseases. The Vaidyas use various contrivances called Yantras for the preparation of
