INORGANIC ANALYSIS 57 APPARATUS, ETC. Improved Farm of Gas-Washing Bottle. F. R. v. Biehowsky and H. Storeh. (J. Amer. Chm. SOL, 1915, 37, 2695-2696.)-The form of bottle described is similar in principle to that suggested by Gumming (ANALYST, 1910, 35, 144). As shown in the figure, the apparatus consists of a bottle, preferably a square medicine bottle, provided with a cork through which pass the inlet and outlet tubes.The gas enters through the lower tube, and forms bubbles at the bend G, these bubbles pass along the tube A, and the gas leaves by the upper tube. The tube A should be of such diameter that the bubbles sweep the liquid through it, thus causing efficient circulation of the liquid in the bottle. The opening C should be about twice the diameter of the tube A.A similar wash-bottle is desoribed which is constructed entirely of glass, and may be used with liquids which attack corks. w. P. s.58 ABSTRACT8 OF CHEMICAL PAPERS Methods for the Estimation of Carbon Dioxide. New Form of Absorption Tower adapted to the Titrimetric Method. E. Torug. (J. I d . and Eng. Chem., 1915, 7, 1045-1049.)-The gravimetric estimation of carbon dioxide by weighing of absorption apparatus gives accurate results for small quantities slowly aspirated; it is important, however, that the drying apparatus before and after the absorption bulbs should have exactly the same drying efficiency.With large amounts of carbon dioxide and rapid aspiration of the gas, the gravimetric method is less accurate and convenient. The method depending on absorption in alkali hydroxide and estimation of the carbonate by differential titration to phenol- phthalein and methyl orange has many disadvantages in accurate work. The influence of the- amounts of-indicator used and the un- certain end-points make the method extremely inconvenient, even under the best conditions. On the other hand, perfectly sharp and accurate titrations can be made with standard barium hydroxide solutions in presence of phenolphthalein.A form of absorption tower for use with barium hydroxide, and suitable for both slow and rapid aspirations, is illustrated (see figure). The apparatus con- sists of a suction flask ( A ) of 500 C.C. capacity, a glass tube (B) 24 inches long by 1 inch diameter, a dropping funnel (E), and a soda-lime tube (a’) in the orifice of the funnel.The bent outlet-tube D has a hole a t E, and to the end of it is attached a glassrod (C) flattened out at the bottom to break up any bubbles which may tend to rise up to the outlet at H. The funnel is charged with 40 C.C. of 0.4 N-barium hydroxide solution from a guarded burette, and the soda-lime tube immediately replaced. After con- necting the funnel to the tower, the apparatus is scrubbed out with air free from carbon dioxide.The baryta solution is then transferred to the tower, and the funnel washed out with 40 to 45 C.C. of water free from carbon dioxide, which is also discharged into the tower. The suction draws the liquid up the tower, keeping the glass beads always moist. Perforated beads should be used, in a, column 16 inches high.After the absorption of the gas, the suction tube is closed and air allowed to pass into the apparatus through the sodaAime tube and stopcock of the funnel. The stopper at the top of the tower is raised, and the extending tubes washed down. The tower is raised a little and tapped until the beads fall into the flask. I t is then washed inside, and at the lower end outside.Titration is made immediately ; the presence of the beads and the barium carbonate does not interfere with the accuracy of the results, but the liquid should be shaken continuously to prevent the local action of the acid on the barium carbonate. J. F. B. Simple Method of Determining the Melting-Points of Fats, etc. A. W. (J. SOC. Ohem. Ind., 1915, 34,1121-1122.)-The substance is plrtcedon the Knapp.APPARATUS, ETC.59 bulb of a thermometer, the latter is fixed in a test-tube by means of a cork, and the test-tube is placed in a beaker containing previously boiled and cooled water, or glycerol ; the test-tube acts as an air-bath. I n the case of fats, waxes, or fatty acids, fine scrspings are taken with the point of a knife over a representative surface of the material, and the scrapings are transferred to the bulb of the thermometer ; they should cover not less than one-half of the bulb.I t is quite easy to see when the sharp outline of the scrapings begins to soften, and also when the fat is completely transparent. For crystalline organic substances the bulb of the thermometer is pushed into the powdered material ; a faint film of powder adheres, and the point st which the substance melts is plainly seen, owing to the fact that the powder reflects irregularly the light coming from the mirror surface of the bulb.w. P. s. Automatic Vaeuum Pump. 0. Maass. (J. Amer. Chern. SOC., 1915, 37, 2654-2656.)-The dia- gram shows a modified Topler pump which, in conjunction with a water-pump, work, automati- cally for an indefinite period.A is the body of the Topler pump, tube P leads to the vessel to be exhausted, and B is the mercury reservoir. At the start the mer- cury stands at the level a in B, and also in the tubes M, E, L, and G. The tube K leads to the water-pump. When the latter is set in action, air is drawn out of A, P, and R, through 1 cm. of mercury in bulb C, and out at K.The pressure over the mercury in B is thus diminished, so that, since tubes E and M sre open to the air, the mercury level in these will be lowered. The volume of B being large compared to the volume of the tubing, the mercury drops gradually to the level d in tube E, whilst the meroury rises to the top of tube L. On L further decrease of the pressure, the mercury in the bottom of bulb D is forced through L and runs down H into B.Air now enters tube H into the water-pump and into B and C, where the pressure is now that of the outside atmosphere. The mercury in bulb C rises in tube r, SO that the presstire in 4 remains equal to that pressure which has been produced by the water-pump. Therefore, the atmofipheric60 ABSTRACTS OF CHEMICAL PAPERS pressure acting on the mercury in B forces this mercury into A, the air in A being forced through the capillary U.At the same time the mercury rises in tube E, quickly at first, and then more slowlyuntil it rises at the same rate that the mercury rises in A . Finally, when the mercury in A reaches the capillary, the mercury in E rushes up to the level b, to whioh level the mercury in B has fallen. I n passing the level e mercury flows into bulb D, preventing further access of air to the water-pump.The pressure in B immediately decreases, so that the mercury is drawn back from A , which latter is now cut off from R by mercury in the capillary II. Simultaneously, the mercury level in E is lowered below level e, and mercury rising in tube L is finally forced into B, so that the atmospheric pressure again presses on the mercury in B.The volume of R is larger than that of A , and the air forced out of A does not increase the pressure in the latter to any great extent. In each cycle, when the pressure over C is decreased sufficiently, air is drawn out of R, so that the pressure in the latter always falls short of the column of mercury in the capillary U. Each time the mercury is driven through the oapillary it rises in V, out of which it is forced back into A when the mercury is leaving the latter, the difference in level of the mercury in U and V becoming equal to the pressure in R. It is essential that tube G be connected to tube F at the same level that E is joined to F. The ends of tubes M and E may be joined to a common glass tap; this is is closed at the start, the air is exhausted by the water-pump, and, on then opening the tap, air enters M and E, and the pump begins to work. A tube and tap may also be attached near the top of tube T, so that air can be admitted at the end of an experiment, w. P. s.