a colorless crystalline substance, c4h6.(oh)4, of a sweet, cooling taste, extracted from certain lichens, and obtained by the decomposition of erythrin; -- called also erythrol, erythroglucin, erythromannite, pseudorcin, cobalt bloom, and under the name phycite obtained from the alga protococcus vulgaris. it is a tetrabasic alcohol, corresponding to glycol and glycerin.-a rose-red mineral, crystallized and earthy, a hydrous arseniate of cobalt, known also as cobalt bloom; -- called also erythrin or erythrine.