<P> Orcein , also archil , orchil , lacmus and C.I. Natural Red 28 , are names for dyes extracted from several species of lichen , commonly known as `` orchella weeds '' , found in various parts of the world . A major source is the archil lichen , Roccella tinctoria . Orcinol is extracted from such lichens . It is then converted to orcein by ammonia and air . In traditional dye - making methods , urine was used as the ammonia source . If the conversion is carried out in the presence of potassium carbonate , calcium hydroxide , and calcium sulfate ( in the form of potash , lime , and gypsum in traditional dye - making methods ) , the result is litmus , a more complex molecule . The manufacture was described by Cocq in 1812 and in the UK in 1874 . Roberts noted orchilla as a principal export of the Cape Verde islands , superior to the same kind of moss found in Italy or the Canaries , that in 1832 was yielding an annual revenue of $200,000 . Commercial archil is either a powder ( called cudbear ) or a paste . It is red in acidic pH and blue in alkaline pH . </P>
<P> Orcein , also archil , orchil , lacmus and C.I. Natural Red 28 , are names for dyes extracted from several species of lichen , commonly known as `` orchella weeds '' , found in various parts of the world . A major source is the archil lichen , Roccella tinctoria . Orcinol is extracted from such lichens . It is then converted to orcein by ammonia and air . In traditional dye - making methods , urine was used as the ammonia source . If the conversion is carried out in the presence of potassium carbonate , calcium hydroxide , and calcium sulfate ( in the form of potash , lime , and gypsum in traditional dye - making methods ) , the result is litmus , a more complex molecule . The manufacture was described by Cocq in 1812 and in the UK in 1874 . Roberts noted orchilla as a principal export of the Cape Verde islands , superior to the same kind of moss found in Italy or the Canaries , that in 1832 was yielding an annual revenue of $200,000 . Commercial archil is either a powder ( called cudbear ) or a paste . It is red in acidic pH and blue in alkaline pH . </P>
purplish dye obtained from lichens also called cudbear
purplish dye obtained from lichens also called cudbear
archil
archil