THE ANALYST. 379 APPARATUS, ETC. The Autolysator : Apparatus Tor the Automatic Estimation of Carbon Dioxide. C. A. Keane and H. Burrows. (Joa~m. SOC. Chenz. Ind., 1908, 27, 608-611.)-The economic importance of the fullest possible control of the combustion of fuel has led to the construction of a number of forms of automatic apparatus for the estimation of carbon dioxide in furnace gases, and it is now recognised that the best plan is to obtain frequent analyses at short intervals. The apparatus giving the most accurate results are those in which the carbon dioxide is determined by an absorption method. In the ‘‘ Autolysator,” the gas to be analysed is drawn by water suction of constant pressure through two similar capillary tubes, each of which is connected with a manometer. A constant flow of gas, carefully regulated, is obtained through the two tubes, and the manometer readings are in each case the same in the absence of any absorbable constituent.Between the two capillary tubes absorption-vessels containing soda-lime are interposed, and the removal in these380 THE ANALYST. vessels of the carbon dioxide causes a difference in the respective pressures, as recorded on the manometers, and thus a means is obtained of determining the presence and amount of carbon dioxide in the furnace gases. Dust and aqueous vapour are removed from the gas before it passes on to the manometer and absorbing- vessels. A recorder is attached to the apparatus, on which the readings of the manometer, showing the amount of absorbed gas, are automatically traced out.The " Autolysator '' gives accurate results when tested against actual volumetric methods in the laboratory, and in works' tests the results obtained by it agree closely with those given by the '' Ados " automatic recorder, A. R. T. New Apparatus for the Determination of the Specific Gravity of Portland Cement. P. Philosophoff. ( C h e m Zeit., 1908, 32, 685.)-The apparatus consists of a conical glass vessel provided with a ground-in neck graduated in & C.C. (from 0 to 2 c.c.), and closed by a stopper carrying a narrow glass tube. This tube is connected by means of a long rubber tube with a second narrow glass tube inserted in the stopper of a burette 0, the jet of which is connected by a short rubber joint with a capillary tube B, which terminates about 0.5 cm.above the bottom of the conical glass vessel. The cement is weighed out in the vessel itself, which for this purpose is provided with a glass stopper (not shown) t o replace the neck A. The apparatus then being connected as above, light petroleum is run into the conical vessel from the burette to any point in the neck between the 0 and 2 C.C. graduations. The volume of the empty vessel having been ascertained in a preliminary experiment, the specific gravity is calculated as usual. L A. G. L. b c Water-Pump with Automatic Non-Return Valve. d (Cham. Zeit., 1908, 32, 542.)--A ground-glass plate, cl, is fitted below the end of the tube c , and is supported by the con- striction on the outer tube, b. The water enters at the top of the apparatus, 20, and passes downwards between the walls n and b ; should the water-supply be interrupted, the air-pressure causes the glass plate to be pressed against the bottom of the tube c, closing the hole 0, so that water cannot be drawn over into the vessel from which the air is being exhausted. w. P. s.