orchilla was shown at the Exhibition, from the Berlingen Isles, from Angola, Madeira and the Cape de Verds.  Orchilla weed is very plentiful about the shores of the islands of New Zealand, some being sent from thence to the Exhibition; but from a want of knowledge as to the time at which it should be gathered, and the mode of preparing it for the market, it has not yet become a saleable commodity there.  The rich varieties of lichens on the rocks and plains of Australia have not been tested, as they ought to be, with Helot’s lichen test.  Various lichens, and Rocella tinctoria, from Tenasserim and other parts of India, have been introduced by the East India Company.  In the Admiralty instructions given to Capt.  Sir James C. Ross, on his Antarctic voyage, a few years ago, his attention was specially called to the search and enquiry for substitutes for the Rocella, which is now becoming scarce.  A prize medal was awarded, in 1851, to an exhibitor from the Elbe for specimens of the weed, and an extract of red and violet orchil.  Specimens of varieties of the lichens used in the manufacture of cudbear, orchil and litmus, and of the substance obtained, were also shown in the British department, which were awarded prize medals.

The beauty of the dyes given by common materials, in the Highlands of Scotland, to some of the cloths which were exhibited, should lead our botanists and chemists to examine, more closely than they have hitherto done, the dye-stuffs that might be extracted from British plants.  Woad (Isatis tinctoria) and the dyers’ yellow woad (Reseda lutea), are both well known.  A piece of tweed, spun and woven in Ross-shire, was dyed brown and black, by such cheap and common dyes as moss and alder bark, and the colors were unexceptionable.

Sutherlandshire tweed and stockings, possessing a rich brown color, were produced with no more valuable dye than soot; in another piece, beautifully dyed, the yellow was obtained from stoney rag, brown from the crops of young heather, and purple from the same, but subjecting the yarn to a greater action of the dye than was necessary to produce brown.  There is very little doubt but that beautiful and permanent dyes, from brown to a very rich purple, might be cheaply procured by scientific preparations of the common heather (Genista tinctoria).  The inhabitants of Skye exhibited cloth with a peculiarly rich dye, obtained from the “crobal” moss.  In the Spanish department, specimens of vegetable dyes from many cultivated and wild plants were furnished by the Agricultural Board of Saragossa, and of several of these it would be important to obtain descriptions and particulars.

Gums are of essential importance to the dyer, and the imports of these, therefore, are large, averaging about 8,000 tons.

INDIGO.