Everything said by the ancients of _Indicum_ seems to agree perfectly with our indigo. The proper country of this production is India; that is to say, Gudscharat or Gutscherad, and Cambaye or Cambaya, from which it seems to have been brought to Europe since the earliest periods. It is found mentioned, from time to time, in every century; it is never spoken of as a new article, and it has always retained its old name; which seems to be a proof that it has been used and employed in commerce without interruption. It is true, as the ancients say, that good indigo, when pulverized, is of a blackish colour. The tincture, however, is partly blue and partly purple; but under the latter term we must understand an agreeable violet, and not, as is often the case, our scarlet. It is true also that good indigo is soft or smooth to the touch[618] when pounded; it floats on water, and at present, as in the time of Pliny, is adulterated and rendered heavier by the admixture of some earth, which in general, as appears, is fine pounded slate[619]. It is further true that the purity of it can be discovered by burning it. Indigo free from all foreign bodies leaves but little ash, while that which is impure leaves a large quantity of earth. Pliny, perhaps, did not rightly understand this test by fire, and added from conjecture, what he says in regard to the colour of the flame and the smell of the smoke, that this proof might not remain without an explanation. It is, however, possible that those who considered indigo to be sea-slime, imagined that they perceived in it a smell of sea-water. A naturalist of modern times, who refers petrifactions to Noah’s flood, believed that he could smell sea-water in them after the lapse of so many thousand years. _Indicum_, on account of its long carriage by land, must have been dear, and therefore it was one of those pigments which the ancient painters, who were often poor slaves, were not accustomed to keep in any quantity by them, and with which it was necessary they should be supplied by those for whom they executed paintings[620]. Our indigo was also exceedingly dear till it was cultivated in the West Indies, where the value of it decreased as long as good land was plentiful and the price of labour was lessened by the slave-trade.