Black: nigrosine black, four ounces, dissolved in one gallon of boiling water.
nigrosine is a black ink, which, although not producing a black so intense as common ink, possesses various advantages.
nigrosine (nī'grə-sēn', -sĭn) or ni·gro·sin (-sĭn)
n.
Any of a class of aniline dyes that vary from blue to black and are used as stains for nervous tissue and as a negative stain for bacteria and spirochetes.
