improved, and particularly by the Chinese. To confound the two substances, however, called indigo (_indicum_) at that period was not possible, as every painter and dealer in colours would know that there were two kinds, a blue and a black. It has, nevertheless, occurred to me, that in the works of the ancients obscurity may have sometimes been avoided by the addition of an epithet; and I once thought I had found in Pliny an instance of this foresight; that is, where he names all kinds of colours--_purpurissum_, _Indicum cæruleum_, _melinum_, _auripigmentum_, _cerussa_[631]. I conceived that in this passage our indigo was distinguished from the black _indicum_ by the epithet _cæruleum_. But my joy at this discovery was soon damped by Hardouin, who places between _Indicum_ and _cæruleum_ a comma, which is not to be found in many of the oldest and best editions. I cannot, therefore, get rid of this comma; for it is beyond all dispute that _cæruleum_ was the common appellation of blue copper ochre, that is, mountain blue. I shall now proceed to examine whether my observation be true, that the Greeks frequently used the term black _indicum_, when they meant to denote the black, and not the blue. The term _nigrum Indicum_ occurs in Arrian, Galen, Paulus Ægineta, and perhaps in the works of other Greek physicians; and as the Latin writers were acquainted with an _Indicum_ which dyed black, there is reason to conjecture that this was the _Indicum nigrum_ of the Greeks, though I should rather be inclined to translate this appellation by the words Indian black, in the same manner as we may say Berlin blue, Roman red, Naples yellow, Brunswick green, Spanish brown, &c.; or I should as readily translate it Indian ink. Arrian introduces it along with other Indian wares. I do not indeed find that he makes any mention of indigo properly so called; but a complete catalogue of merchandise is not to be expected from him. _Indicum_, however, occurs once more in this author; but in the passage where it is found it is only an epithet to another article. Speaking of cinnabar, he adds, that he means that kind called Indian, which is obtained from a tree in the same manner as gum. I am inclined to think that he alludes to dragon’s blood, which on account of its colour was at that time called cinnabar.