a fungus, of which some of the principal species have been described in the Encyclopaedia under the generic name Agaricus. There is, however, one species not mentioned there—the Boletus birutus of Bulliard, which is certainly worthy of notice, since one of the French chemists has lately extracted from it a bright, shining, and very durable yellow dye. This pretty large mushroom grows commonly on walnut and apple-trees. Its colouring-matter is contained in abundance, not only in the tubular part, but also in the parenchyma of the body of the mushroom. In order to extract it, the mushroom is pounded in a mortar, and the liquor thence obtained is boiled for a quarter of an hour in water. An ounce of liquor is sufficient to communicate colouring-matter to five pounds of water. When the liquor has been strained, the fluff to be dyed is put into it, and boiled for a quarter of an hour. All kinds of stuff receive this colour and retain it; but on linen and cotton it is less bright. This colour may be modified, in a very agreeable manner, by the effect of mordants.

The process succeeded best on silk. When this substance, after being dyed, is made to pass through a bath of soft soap, it acquires a shining golden yellow colour, which has a perfect resemblance to the yellow of that silk employed to imitate embroidery in gold, and which has hitherto been brought from China and sold at a dear rate, as the method of dyeing it is unknown in Europe. The yellow colour extracted from this mushroom may be employed also with advantage for painting in water colours as well as in oil.