The wine test sometimes employed is prepared in the following manner:--Mix equal parts of finely powdered sulphur and of slacked quick-lime, and expose it to a red heat for twenty minutes. To thirty-six grains of this sulphuret of lime, add twenty-six grains of super-tartrate of potassa; put the mixture into an ounce bottle, and fill up the bottle with water that has been previously boiled, and suffered to cool. The liquor, after having been repeatedly shaken, and allowed to become clear, by the subsidence of the undissolved matter, may then be poured into another phial, into which about twenty drops of muriatic acid have been previously put. It is then ready for use. This test, when mingled with wine containing lead or copper, turns the wine of a dark-brown or black colour. But the mere application of sulphuretted hydrogen gas to wine, acidulated by muriatic acid, is a far more preferable mode of detecting lead in wine. M. Vogel[39] has lately recommended acetate of lead as a test for detecting extraneous colours in red wine. He remarks, that none of the substances that can be employed for colouring wine, such as the berries of the Vaccinium Mirtillus (bilberries), elderberries, and Campeach wood, produce with genuine red wine, a greenish grey precipitate, which is the colour that is procured by this test by means of genuine red wines. Wine coloured with the juice of the bilberries, or elderberries, or Campeach wood, produces, with acetate of lead, a deep blue precipitate; and Brazil-wood, red saunders, and the red beet, produce a colour which is precipitated red by acetate of lead. Wine coloured by beet root is also rendered colourless by lime water; but the weakest acid brings back the colour. As the colouring matter of red wines resides in the skin of the grape, M. Vogel prepared a quantity of skins, and reduced them to powder. In this state he found that they communicated to alcohol a deep red colour: a paper stained with this colour was rendered red by acids and green by alkalies. M. Vogel made a quantity of red wine from black grapes, for the purpose of his experiments; and this produced the genuine greyish green precipitate with acetate of lead. He also found the same coloured precipitate in two specimens of red wine, the genuineness of which could not be suspected; the one from Chateau-Marguaux, and the other from the neighbourhood of Coblentz. SPECIFIC DIFFERENCES, AND COMPONENT PARTS OF WINE.