THE ANALYST. 131 APPARATUS. A Form of Burette for avoiding Errors in Titration at the Boiling- point. H. Gockel. (Chem. Zeit., 1905, xxix., 1208.)-A modification of Koninck’s burette, in which the exit-tube comes out at right angles to the main tube. In the present type the side tube is not horizontal, but curves up somewhat and then down again. This avoids the necessity of placing the burette at a high level. The burette can be obtained from Dr. H. Gookel, Berlin, W. E. K. H.132 THE ANALYST. Heating under Reduced Pressure by the Aid of an Electric Oven. E. Haagn. (Chem. Zeit., 1905, xxix., 1209.)-The accompanying figure shows a very useful form of electric oven, furnished with an arrangement for giving a partial vacuum. The bottom portion of the appa- ratus is made with a double wall, between which water circulates, being admitted by the aperture B, and running off by aperture A.In consequence of this cooling, the top can be safely provided with a rubber fitting, which insures an air-tight joint. The oven is exhausted by means of the tube C, connected to a water-pump. The oven itself is a modification of that designed by W. C. Herams, of Hanover, but, in contrast to the earlier models, the heating resistance is within the mass of the oven body. This gives greater heat economy in working, and causes the highest temperature to be more quickly attained. A temperature of l l O O o C. can be obtained, and this is reached in about twenty to twenty-five minutes. About 8 kilowatt is used. For ordinary purposes a good water-pump gives a sufficiently reduced pressure ; but, of course, any desired reduction can be obtained by the ordinary means.The advantages of heating in a partial vacuum are often very great. Thus marble, which requires a good half-hour in a gas furnace for complete conversion to lime, is, in the present apparatus, completely converted in three minutes after the full temperature is attained. By first exhausting and then admitting any gas, it is easy to use this apparatus for heating substances in an atmosphere of any desired gas. The advantages of electric heating are also obtained by this oven. The influence of gas flames on platinum crucibles is especially bad, and the avoidance of this evil is almost a sufficient recommendation. E. K. H. An Improved Pattern of Gooch Crucible.H. Vollers. (Chem. Zeit., 1905, xxix., 1088.)-The principle of this form of crucible is clearly indicated in the accompanying figure. In place of the usual perforated bottom, there is a raised cylinder with the holes passing through the wall, the direction of the holes being parallel to the bottom. By this device the author claims to have removed the defect shown by an ordinary Gooch crucible, that the pores get blocked up by the asbestos; the asbestos can be pressed down very firmly, and, if the filtration is then too slow, some of the holes, usually only a, few, can be cleared by means of a bent needle. The crucible is supplied by the firm of C. Gerhardt, Bonn a. Rh. E, K. H.THE ANALYST. 133 A Constant Temperature Bath for Low Temperatures. A.Given. (Journ. Amw. Chem. SOC., 1905, xxvii., 1519.)-The bath shown in Fig. 1 was FIG. 1. designed originally to keep pyk- nometers at a constant tempera- ture of 15.6" C.; but it has since been found to work well at other moderately low temperatures. In principle it consists essentially of a bath of distilled water, in which the greater part of the pyknorneter is immersed, and which is cooled by an ice-box, and heated by a Bunsen burner (not shown) fitted with a gas-regulator. The bath itself is double-walled, the space between the outer galvanized iron wall and the inner copper wall being packed with asbestos. The ice-box I is of copper, and fitted with a wooden cover. I t is raised 14 inches above the bath, so as to leave space for an overflow-pipe, and it extends to within 14 inches from the bottom of the bath.A gentle current of air is introduced close to the bottom of the ice-box, and serves to stir the water in the outer bath, The pyknometers stand on the perforated shelf P, supported on hangers, which also carry the narrow shelf S for the thermometer and gas-regulator. This last is shown in Fig. 2, and consists of a large bulb, A , 5 inches long and 1 inch in diameter, filled with methyl alcohol (toluol might be even better), M represents the mercury seal, R being a rod of glass to strengthen the apparatus. The gas enters at I and leaves at 0 ; at P there is a hole for the pilot-flame I n using the bath, the pyknometers are first of all cooled to about 14" C., and then only placed in the bath, in which they may remain for any reasonable time, A 50 pounds of ice in seven hours in the hottest weather, but less than 1 pound of ice in it will keep the temperature of the bath constant.d -- supply* bath, 18 inches square and 12 inches deep, consumes about &-- FIG. 2. A. G. L.134 THE ANALYST. A Modification of Gintl's Pyknometer. M. Raukusin. (Chew. Zeit., 1905, xxix., 1087.)-The author brings forward a modified form of apparatus, the design of which is seen in the accompanying figure. The sample of fat is contained in the cylinder a, which in this form is open at both ends. The lower end of this pyknometer tube is ground to fit the glass cap k, which is ground on the inside, and thus a tight joint closes the tube. On the upper edge of the pyknometer tube a glass cover, b, is laid, which closes the tube 3 dl K C , tube fits exactlv with the canal in the cover.The whole tightly through receiving the wall of the tube in a small annular canal. The apparatus is used as follows : The three portions of the instrument are carefully cleaned and dried. The tube a is then placed in the cap k, and filled with the melted fat. The cover b is then laid on the tube, so that the wall of the .I instrument is then placed in a metal clamp, shown in the figure, and the excess of fat removed by pressure from the screwf, and the instru- ment then washed with petroleum ether and cleaned with chamois leather. The fat can be removed from the cylinder by a glass rod, the last traces being h got rid of with ether, etc. A New Crucible Triangle. A. Kette.(Chem. Zeit., 1905, xxix., 1208.)-The author points out the failings of the ordinary pipeclay triangle and the platinum triangle. In particular all forms suffer from the defect that the flame is broken on the bottom of the crucible, and its further heat- ing power is thus lost. To remedy this defect, the author brings forward the arrangement shown in the figure. The crucible rests on the angles of the three prisms, and the flame touches only fire-resisting material. The ring surrounding these pieces can be tightened and loosened by means of the small screw, and the opening thus altered to 5 t various-sized crucibles. Finally, the effective heating of any given flame is much increased, as very little of its power is lost. The author states that a platinum crucible can be easily and quickly raised to L temperature of 1300" C.This apparatus can be obtained from the firm of Bender and Hobein, Munich. E. K. H. E. K. H.THE ANALYST. 135 A New Vacuum Filter for Laboratory and Domestic Use and a wholly Novel Method of Cleaning the Filtering Material. (Zeits. angew. Chem., 1906, xix., 95.)-In the vacuum filter described the filtering material may be easily cleaned by evacuating the upper part of the ap- paratus by means of the pump p , as shown in Fig. 1, air being sucked in through the opening F below the filter. As soon as the filter is thoroughly clean, the liquid in A will become filled with small air - bubbles. The air admitted through F may be previously sterilized in any convenient way. Fig. 2 shows the normal way of working the apparatus as a filter.I t may be obtained of the following firms : Warmbriinn, Quilitz and Co., Berlin, N.W., Haidestrasse 55 to 57 ; Albert Dettloff, Berlin, N.W., Luisenstrasse 59 ; Franz Hugershoff, Leipzig. FIG. 1. FIG. 2. A. G. L. Apparatus for Continuous Extraction of Liquids with Ether, Benzene, or other Solvent. R. S. Bow- man. (Proc. Ch-em. Soc., 1906, xxii., 24.)-The apparatus described obviated the use of numerous corks and rubber joints, and may be easily constructed in the laboratory. The flask A, which may frequently be replaced by a wide test-tube, is filled almost to the neck with the liquid to be extracted, one-eighth to one-fifth of this volume of solvent being placed in the flask B, which is suitably heated. The vapour passes up the tube C, is condensed, and falling back, collects in the inner tube D, forming a column of liquid which in time becomes long enough to force its way through the liquid in A, and small drops of solvent, ascending in A, collect on the surface of the liquid, and finally overflowing at F, return to the flask B.On completion of the extrac- tion, the solvent is run off from the neck of the flask by opening the stop-cock E. W. H. S. ETHE ANALYST. 136 La ID Apparatus for Removing Gases from Aerated Liquids before Determining the Specifie Gravity of the Latter. K, Ulrich. (Chem. Zed., 1906, xxx., 90.)-The liquid is filled into the cylinder A and drawn into the bulb B by attaching the pipe L to an air-pump, the taps C and D being turned to give the necessary connections. The tap C is then closed, and the action of the pump allowed to proceed until the gases have been com- pletely removed from the liquid in B. Air is now admitted by turning the tap D, and the liquid allowed to flow back again through the tap C into the cylinder A, where its specific gravity is taken by means of a hydrometer. The short tube below the Note on a Combined Wash-Bottle and Pipette, J. W. Hogarth. (Chem. News, 1906, vol. 93, p. 71.)-By inserting the apparatus shown in an ordinary wash - bottle flask, a, measured volume of solution may be delivered from the jet of the wash-bottle. The measuring vessel a, which is fitted with a jet and the mouth-piece f, is filled by raising the rod d, which closes the lower orifice, d’, of a, and by blowing into the wash-bottle flask through the rubber-tube h. As soon as a i s filled to the desired extent, the rod d is released, when the rubber-tube e, which connects d and the short piece of glass-tubing in the stopper through which it passes, forces the rod back into position, so as to close the lower opening of a. The vessel a is capable of holding 15 c.c., and of delivering any less quantity with an error of only + C.C. A. G. L.