Spain exhibited various vegetable dyes obtained from cultivated and wild plants furnished by the Agricultural Board of Saragossa.

LICHENS.

The chief lichens employed in the manufacture of orchil and cudbear are the following:—­

Angola weed (Ramalina furfuracea).

Mauritius weed (Rocella fusiformis), which comes also from Madagascar, Lima, and Valparaiso, and then bears the distinctive commercial name of the port of shipment.

Cape weed (Rocella tinctoria), from the Cape de Verd Islands.

Canary Moss (Parmelia perlata).

Tartareous Moss (Parmelia tartarea).

Pustulatus Moss (Umbilicaria pustulata).

Velvet Moss (Gyrophora murina).

The last three are imported from Sweden.

Of these lichens, the first, which is the richest in coloring matter, grows as a parasite upon trees; all the remainder upon rocks.

Rocella corallina, Variolaris lactea and dealbata, have been also resorted to.

About 130 tons of cudbear are imported annually from Sweden.

These lichens are found on rocks, on the sea coast.  The modes, of treating them for the manufacture of the different dyes is the same in principle, though varying slightly in detail.  They are carefully cleaned and ground into a pulp with water, an ammoniacal liquor is from time to time added, and the mass constantly stirred in order to expose it as much as possible to the air.  Peculiar substances existing in these plants are, during this process, so changed by the combined action of the atmosphere, water, and ammonia, as to generate the coloring matter, which, when perfect, is pressed out, and gypsum, chalk, or other substances, are then added, so as to give it the desired consistency; these are then prepared for the market under the forms of cudbear or litmus.

HENNA (Lawsonia inermis), is an important dye-stuff, and the distilled water of the flowers is used as a perfume.  The Mahomedan women in India use the shoots for dyeing their nails red, and the same practice prevails in Arabia.  In these countries the manes and tails of the horses are stained red in the same manner.  The Genista tomentosa yields red petals used in dyeing, and containing much tannic acid.

ORCHILLA WEED.—­The fine purple color which the orchilla weed yields, is in use as an agent for coloring, staining, and dyeing.  About 30,000 lbs. is obtained annually in the island of Teneriffe. 460 arrobas (or 115 cwt.) of orchilla were exported from the Canary Isles in 1833.  In 1839, 6,494 cwts. paid duty, and 4,175 cwts. in 1840.  The average imports of the three years ending with 1842, was 6,050 cwt.  A little comes in from Barbary and the islands of the Archipelago.

Dr. W.L.  Lindley, in a very interesting paper, read before the Botanical Society of London, in December, 1852, on the dyeing properties of the lichens, stated—­