THE CHEMICAL GAZETTE No. CCCXCII.—February 15, 1859. SCIENTIFIC AND MEDICINAL CHEMISTRY. On the Yellow Colouring Mutter and the Tannic Acid in Thuja occidentalis. 13>j M. Kawalier. The following investigation, recently communicated by Dr. Roch- leder to the Vienna Academy, was made by Kawalier in his labo ratory. The fronds of Thuja, reduced to small fragments, are boiled with alcohol, and the decoction strained from the undissolved material through linen. On cooling, much w'ax is deposited from the de coction, and collected on a filter. The filtered fluid is distilled in the water-bath, and the residue mixed with more water, by which means resin and w 7 ax are separated. The turbid fluid stops the pores of the filter, so that it cannot be filtered. It is therefore mixed with a few drops of solution of acetate of lead. The sus pended impurities are carried down by the small quantity of preci pitate produced, so that the fluid may be easily filtered. The filtrate is of a brownish-yellow colour and clear; when mixed with neutral acetate of lead it gives a yellow precipitate, which is collected upon a filter, and washed with water. It is then dissolved in dilute acetic acid; the solution is filtered from any undissolved portion, and the filtrate precipitated with basic acetate of lead. The beauti ful yellow precipitate is washed with water, first by decantation, then upon a filter, and then suspended in water and decomposed by a current of sulphuretted hydrogen. The fluid is heated to boiling together with the sulphuret of lead, and filtered upon a water-bath funnel. The sulphuret of lead is washed with a little hot water. The filtrates are heated in a current of carbonic acid until the sul phuretted hydrogen is expelled, and then placed in capsules over sulphuric acid under the bell of the air-pump. After standing for several days, a yellow, crystallized substance separates. The cry stals are collected upon a filter, and dissolved in boiling water, to which small quantities of strong alcohol are added until the solution Chem. Gaz. 1859. e