INORGANIC ANALYSIS 419 APPARATUS, ETC. Apparatus for Continuous Extraction of a Liquid by Another and Heavier Liquid. J. Greenwald. (J. Ind. and Eng. Chent., 1915, 7, 621.)-The apparatus figured is constructed of glass. In use, some of the heavy liquid is poured into A. The liquid to be extracted is then added until the heavy solvent is forced up the tube C almost to its opening into B. The apparatus is then connected, in the usual manner, to a flask containing more of the solvent and to a condenser.Chloroform will extract all the caffeine from a 2-5 per cent. aqueous solution in three hours. G. C . J.420 ABSTRACI'S OF CHEMICAL PAPERS New Form of Pyknometer for Liquids. P. B. Davis and L. S. Pratt. ( J . Amer. Chem. SOC., 1915, 37, 1199-1200.)l -An improved form of Sprengel pykno- e F meter consists of a single closed tube of thin glass of the desired capacity, into the top of which are fused two capillary tubes.One of these, which is attached centrally, is bent a little above its point of emergence to an angle of 60°, and drawn out slightly at the end. This capillary is continued axially in- side the reservoir in the form of a tapered thin glass tube reaching alaost to the bottom, and having a bore at the lower end approximately equal to the capillary bore.The other capillary, attached slightly towards the side of the reservoir, is bent at a right angle, its bore in the vertical portion being swelled out into a small bulb sufficient to accommodate the expansion of the liquid over a rise in temperature of 10" C.A mark is etched on this capillary just below the taper of the bulb. The apparatus has the" appearance of a tubular wash-bottle. I n OJ adjusting the instrument when filled, a rubber tube is attached to the right-angled capillary, and the liquid blown gently out of the other until its level corresponds with the mark. The point is wiped with filter-paper, and, on removing the pressure, the liquid falls back in the inclined capillary, thereby reducing the danger of evaporation or accidental loss after adjustment.The advantages of this form of pyknometer are minimum weight, minimum length and projection of capillary arms, ease of cleaning and drying. J. F. B. Synthermal Regulator. A Device for Automatically Main- taining an Adiabatic Condition in Calorimetry.T. W. Richards and G. D. Osgood. ( J . Amer. Che.m. SOC., 1915, 37, 1718-1720.)- A differential hydrogen thermometer with a sensitive mercury contact is shown in the illustration. This apparatus, with the help of a relay, enables a stronger current to operate a heating or cooling mechanism for causing the temperature of one bath to follow that of another within 0.03O C. Two copper or silver cylinders, H, are cemented to a narrow glass U-tube, U ; suitable taps, A , 23, and C, are provided, so that the apparatus may be filled with hydrogen, and the platinumREPORT 421 wire E, containing 8 per cent. of iridium, is sealed into one of the bulbs of the U-tube so as to make contact with the mercury at the widening of the U-tube. The apparatus is extremely sensitive, and will make and break contact within O.Ol0 c. w. P. s.