dyer’s orchil.
569
Fig. 72.
a close vessel with a wine-pint of boiling water, then to be boiled forfifteen minutes, and the liquor strained while hot.
Rocel'la tincto'ria, De Cand. L.D.— Dyer's Orchil or OrcheXla.
Sex. Syst. Cryptogamia, Algae .
(Lacmus: Thallus praeparatus, Ph . Lond. Litmus, Ph . Dubl.)
History 7 . — It is the wivnov <$>vkoq ( Fucus marinus) of Theophrastus (Hist. Plant, lib. iv. cap. 7). By the moderns it was first employed asa dye at the commencement of the fourteenth century (Beckmann, Hist.°f Invent, and Discov. i.)
Botany. Gen. Char. — Thallus coriaceo-cartilaginous, rounded orPlane, branched or laciuiated. Apothecia orbicular, adnate rvith the*1'all us; the disk coloured, plano-convex, with a border at length thick-® n ed and elevated, formed of the thallus, and covering a sublentiform,black, compact, pulverulent powder concealed within the substance(Hooker).
Sp. Char. — Thallus suffruticose, rounded, branched, somewhat erect,
greyish brown, bearing powdery warts.Apothecia flat, almost black and pruinose,with a scarcely prominent border (Hooker).
Hab. —Maritime rocks of the Cana-ries, Azores , southern coast of England,&c.
Commerce. —It is imported in bagsfrom the Canaries ( Canary Weed), theAzores ( Western Island Weed, St. Mi-chael's Weed), Cape de Verde Islands andMogadore (African or Mogadore Weed).That from the Canaries is the most valu-able. In 1838, 567 cwts. oiRocella tinc-toria and fuciformis paid duty.
. Physical Properties. —Both Rocella tinctoria and fuciformis are^Ported as orchil. I have met with the latter species in commerceI der the name of Madeira Weed. It is distinguished from R. tinctoria
y Us larger size, its paler colour, and its broader flat fronds.
Composition. —Rocella tinctoria was analyzed by Fr. Nees v. Esenbeck,I bo found in it a brown resin (soluble in alcohol and ether, and becomingbanish red with ammonia), wax, glutinous matter, insoluble starch,ou> extractive, yellowish brown gummy matter, lichenin, tartrate and
Rocella tinctoria.a. Warts on the thallus.
of lime, and chloride of sodium from the adherent sea waterees v. Esenbeck and Ebermaier, Handb. d. med.pharm. Bot. Bd. 1.)
Con* 1 ® su b s tance which, under the influence of ammonia and air, yields the purpleC'A Ur,n S matter of this plant, has been denominated, by Heeren (Thomson’s Org.en }- 401), erythrin. It is white, tasteless, odourless, fusible, combustible, insolublein 170 parts of boiling water, and more soluble in alcohol. The samep 05 , lst has also obtained from this plant a crystalline fatty acid (rocellic acid), com-ea of H 16 O 4 .
tirf ClIKMICAL Characteristics. —The aqueous decoction of RocellaCol c o to ria forms a copious precipitate with diacetate of lead, and has its^ Ur deepened by alkalies. Digested in a tveak solution of ammonia,c 9 r ked phial, at a heat not exceeding 130° F., this plant yields aVl olet-red colour. This is Hellot’s test for the discovery of a colorific