_Lepraria chlorina._ Brimstone coloured lepraria. Scandinavia, on rocks. _L. Iolithus._ Viol-massa. Sweden, on stones. Gives stones the appearance of blood stains. _Parmelia omphalodes._ In Scandinavia and Scotland. Withering asserts it yields a purple dye, paler, but more permanent, than orchil; which is prepared in Iceland by steeping in stale lye, adding a little salt and making it up into balls with lime. _P. parietina._ Common yellow wall lichen, Wag-massla Wag-laf. England and Sweden, on trees, rocks, walls, palings. Used to dye Easter eggs. Used in Sweden for wool dyeing. _P. physoides._ Dark crottle, Bjork-laf. Found in Sweden, Scotland and Scandinavia, on rocks and trees. _Sticta pulmonacea._ Oak lung, Lungwort, Aikraw Hazelraw, Oak-rag, Hazel crottle, Rags. Found on trees in England, Scotland, North of Ireland, Scandinavia. It dyes wool orange and is said to have been used by the Herefordshire peasantry to dye stockings brown. Some species yield beautiful saffron or gamboge coloured dyes, e.g. _S. flava crocata, aurata_. _S. scrobiculata._ Aik-raw, Oak rag. Found on trees in Scotland and England. FOOTNOTES: [Footnote D: From an article by Dr. Lauder Lindsay on "The Dyeing Properties of Lichens." _The Edinburgh Philosophical Journal_, July to October, 1855.] CHAPTER V BLUE INDIGO, WOAD, LOGWOOD _INDIGO_ Indigo is the blue matter extracted from a plant _Indigofera tinctoria_ and other species, growing in Asia, South America and Egypt. It reaches the market in a fine powder, which is insoluble in water. There are two ways of dyeing with Indigo. It may be dissolved in sulphuric acid or oil of vitriol, thereby making an indigo extract. This process was discovered in 1740. It gives good blue colours but is not very permanent, darker colours are more so than the paler. It does not dye cotton or linen. The other method is by the Indigo vat process which produces fast colours but is complicated and difficult. In order to colour with indigo it has to be deprived of its oxygen. The deoxidized indigo is yellow and in this state penetrates the woollen fibre; the more perfectly the indigo in a vat is deoxidized, the brighter and faster will be the colour. For wool dyeing the vats are heated to a temperature of 50 deg.C. Cotton and linen are generally dyed cold. TO MAKE EXTRACT OF INDIGO 1 lb. oil of vitriol (pure, not commercial). 2 oz. finely ground Indigo. 1/2 oz. precipitated chalk. Mix a little of the indigo with a small quantity of oil of vitriol, add a little chalk and stir well. Go on mixing gradually till all is used up. This should take an hour or two. Stir a few times each day for 4 or 5 days, adding about 1/2 oz. more of chalk by degrees. It is best mixed in a glass stoppered bottle or jar, and stirred with a glass rod. It must be kept from the air. INDIGO EXTRACT (4 to 6 lbs. wool).