328

INDIGO.

shades, indigo cannot he dispensed with where its hue shouldappear.

The last named pigment, smalt, we understand, will notharmonize with other colours in oil painting, so well as willindigo. With reference to the view Dioscorides took ofindicon, from the circumstance of its being prepared incopper vessels, it may not be safe to use it at all times asan internal medicine; and such are the advantages which mo-dern chyinistry has secured to us, that discoveries of othermedicines are made which answer those purposes muchbetter.

Dioscorides also names another kind of indigo, which, hesays, was the coloured scum of the dye-pans, dried. Thisaccount has been, heretofore, considered by commentatorsas merely conjectural in that naturalist. A blue pigment,however, and one remarkably line, if the previous prepara-tions hail been properly made, will be found to result fromthis process. It is true, it is not indigo, but certainly verynearly of a similar nature.

A certain tine and valuable powder, sold at present underthe name of blue carmine, the preparation of which is not yetproperly ascertained, is conjectured to be produced in thismanner: in the liquor of a blue dye-pan, are observed to floatthe finer particles of many colours; among these the ancientTyrian purple. So that the description of Dioscorides appearsperfectly clear; especially as it is proved this pigment maybe collected from a dye made from woad; and as those dyers,at the end of the sixteenth century, we are told, separatedfrom their pans a colouring substance, they sold in thestead of indigo.

In establishments for dyeing black, in ancient times, thescum was collected for a black pigment, which practice aprpears to have been quite common. Why, then, should nota purple dye have been collected in the same manner, butto form purple-coloured carmine.

It also appears quite evident, that the Indkum nigrum ofPliny , was what we, at present, use under the name ofIndian ink. Vitruvius also expresses himself in nearlysimilar terms with Pliny . For, he says, the ancients hadlints, in which they burnt pine-wood, where the smoke beingcollected, they formed lamp-black from it, which, he says,if properly made, as well as ivory black, formed as good acolour and made nearly as good ink as the Indkum.

The ancients, it also appears, had a favourite black fromthe same process which the moderns now use to obtain theirnoir dc vigne, or Frankfort black, which our copper-plate