The block tin condensing tubes should be about ⅜ of an inch inner measure and seven in number, entering the tank through holes in the front side of it near the top above the level of the overflow, and pass down perpendicularly through the tank and out through the rubber stoppers, tightly fitted into holes in the bottom; they should project 1½ inches below the bottom of the tank, and connect by short rubber tubes, with glass bulb tubes, of the usual shape, which dip into glass precipitating beakers. These beakers should project about 6½ inches high by 3 inches in diameter below, gradually narrowing above, and should be about 500 cubic centimeters capacity. The titration can be made directly in them. The seven distillation flasks should be supported on a sheet-iron shelf attached to the wooden frame which supports the tank at the front; where each flask is to stand, a circular hole should be cut with three projecting lips to support the wire gauze under the flask, and three other lips to hold the flask in place, and to prevent its moving laterally out of place while distillation is going on. Below the sheet-iron shelf should be a metal tube carrying seven Bunsen burners, each with a stopcock like those of a gas combustion furnace. These burners are of larger diameter at the top, which prevents smoking when covered with fine gauze to prevent the flame from striking back. (14). The stand for holding the digestion flask should consist of a pan of sheet iron, 29 inches long by 8 inches wide, on the front of which is fastened a shelf of sheet iron as long as the pan, 5 inches wide and 4 inches high. In this are cut six holes 1⅝ inches in diameter. At the back of the pan is a stout wire running lengthwise of the stand, 8 inches high, with a bend or depression opposite each hole in the shelf. The digestion flask rests with its lower part over a hole in the shelf and its neck in one of the depressions in the wire frame, which holds it securely in position, and heat should be supplied with Bunsen burners below the shelf. THE DETERMINATION One gram of the substance to be analyzed is brought into a digestion flask with approximately 0.7 grams of mercuric-oxide, and 20 cubic centimeters of sulphuric acid, and the flask is placed on the frame described in an inclined position, and heated below the boiling point of the acid for from five to fifteen minutes, or until frothing has ceased. The heat is then raised until it boils briskly. No further attention is required until the contents of the flask have become a clear liquor, which is colorless, or, at least, has only a very pale straw color. The flask is then removed from the flame, held upright, and, while yet hot, potassium permanganate is dropped in carefully and in small quantities at a time until, after shaking, the liquid remains of a green or purple color.