422 THE ANALYST. APPARATUS. On a Petroleum Coke for Metallwrgieal Laboratory Use. F. 0, Doeltz. (Clzem. Ztg., 1906, xxx., 585.)-The Celle-Wietze Petroleum Company in Hanover are supplying a petroleum coke well suited for many uses in the laboratory and for the manufacture of electrodes. I t forms a pitch-black, shining, porous mass of consider- able mechanical strength. Its calorific value was determined at 7,330 calories ; its ash content varies from 0.21 to 0.53 per cent. The ash shows a tendency to fuse from the presence of alkali. The production in the year 1905 was 55,000 kilogms. of the coke, its present price being 5 marks per 100 kilogms. A. G. L. A New Method for the Standardization of Thermometers below 0" C. T. W. Richards and F. G. Jackson. (Proc. Amer. Acad., 1906, vol.41, p. 21; through Chern. Ztg., 1906, xxx., Rep., 261.)-The thermometer is standardized by means of solutions of known melting-points. For this purpose the thermometer is placed in a, mixture of ice and water. The substance is then added and the thermo- metric reading obtained noted. Finally, the concentration of the substance added isTHE ANALYST. 423 determined analytically in the solution obtained, the real melting-point of a solution of this strength being then ascertained by reference to a table. I n this way any number of points may be determined, and a curve of correction for the particular thermometer may be constructed, A. G. L. A New Sodium Burner, (Chem. Ztg., 1906, XXX., 835.)-The new burner, which is made by Carl Zeiss, consists essentially of a Bunsen burner provided with a nozzle (C), and a small salt tray, which can be adjusted at the edge of the flame by a screw ( J ) .The tray consists of plate of pumice, 4 x 1 x $ cm., which is soaked in a solution of salt before use. The light from the flame passes through a rectangular hole ( L ) , 4 x 5 cm., cut in the screen (K), so as to yield a steady iinage of even intensity. ' A. G. L. On a New Electrically-heated Microscope Stage. J. Zwintz and C. Thien. (Zeiztralbl. Bakter.ioZ., 1906, [l], vol. 42, p. 179 ; through Chem. Ztg., 1906, xxx., Bep., 341.)-The stage is heated electrically and provided with an automatic regulator. This consists practically of an air manometer, one limb of which is closed at one end and connectedto a U-tube containing mercury at the other, At the bend of the U-tube a platinum contact-piece is sealed through the glass, whilst a graduated metallic rod is pushed to a certain depth into the open limb of the U-tube.If now the stage is heated to the desired temperature, the air in the closed limb of the manometer expands, pushing the mercury in the U-tube before it, and so making contact between the platinum contact-piece and the metallic rod. This closes the circuit of a battery which works a contact-breaker included in the heating circuit, and thus cuts off the latter. A. G. L. Weighing Bottle for Liquids. K. Buschmann. (Chenz. Ztg., 1906, xxx., 1060.)-To use the weighing bottle shown in the figure, some of the liquid is poured into it, and the hollow stopper is inserted so that the hole (e) in the stopper is not opposite the groove (a) in the neck of the bottle. The bottle is then weighed, the stopper turned so as to bring (e) opposite (a), and some of the liquid is forced out by compressing the india-rubber ball on the stopper, which is then again turned into its first position, after which the bottle is again weighed. The bottle may be obtained from F. A. Kiihnlenz, Frauenwalde i. Th., Germany. A. G. L.