TEST-LIQUOR, a liquor used by dealers in brandies, to prove whether they be genuine, or mixed with home-spirits. This liquor is nothing but a green or white vitriol, dissolved in fair water; for a few drops of it being let fall into a glass of old French brandy, will turn the whole to a purple, or fine violet colour; and by the strength or paleness of this colour, the dealers judge the brandy to be genuine or mixed, in different proportions, with home-spirits.