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To Detect Logwood in Wine

M. Lapcymere, having observed that hæmatine, the coloring principle of logwood, gives a sky-blue color in the presence of salts of (georgina purpurea); alkalies turn it green; copper, proposes the following test for logwood in wines: Paper is saturated with a strong solution of neutral acetate of copper, and dried. A strip of this is dipped into the fuspected liquor, and, after removal, the adhering drops are made to move to and fro over the paper, which is finally to be carefully dried. If the wine contain logwood, the paper will assume a violet-blue color; but if the wine possess its natural coloring matter the paper will have a grey tint. acids, red; strong caustic alkalies turn it yellow. This is a very delicate test paper.

The juice of elderberries will make a similar test paper.