ANALYTICAL EDITION
112
Vol. 1, No. 2
pletely displaced by mercury. After adjustment of the mercury so as to fill D, the vacuum in F can be broken. Then C closes, H opens, and the distillate drains into J overflowing into an appropriate receiver. To hasten the emptying of F, pressure may be applied a t M .
This method of cutting fractions is being used on several stills, varying from a micro-apparatus of 10 cc. capacity to one handling 5 liters, in which about 50 liters of bases from California kerosene stock are undergoing exhaustive fractional distillation.
Air Separator for the Laboratory’
ciently to drop out the coarser material. The finer particles. are further carried by the air current through the openings just below the cover and into the central space, where they are deposited. They may be recovered, without removing the stocking, through the hole which is closed with the stopper. Any material which is carried past this chamber is arrested in the stocking filter. With a little experience an operator can control the degree of separation as desired by changing t h e amount of compressed air to the aspirator.
R. E. Zinn VICTORCHEMICALWORKS, CHICAGO, ILL.
experimental work with finely ground solids it is InotNoften necessary to obtain a physical separation which is readily done with the regular 100- to 200-mesh sieves. This is particularly true in cases where the material does not screen easily because i t is too light or because the particles adhere to one another; also, it may he desired to effect a separation of material finer than 200 mesh. Under these conditions the desired result is most readily obtained by means of air separation. A convenient air separator suitable for qualitative separation has been successfully built and used by the writer. Such a device may be easily and quickly made from materials that are generally available about A laboratory. Its construction will be evident from the accompanying sketches and the description which follows.
Secure a 5-pound (2.3-kg.) can, a 2-pound (0.9-kg.) can, and a l/rpound (0.23-kg.) can. Cut openings and tongues in the 2-pound can as in Figure 1. Also cut a 1-inch hole in the bottom and insert a stopper. Cut slots in the 5-pound can cover to fit the tongues; cut a hole in this cover to fit the ‘/p-pound can, which has had the bottom cut out of it. Make a hole for the inlet tube as shown in Figure 2, and secure the tube to the can tangentially with deKhotinsky cement. Seal the pieces fitted through the cover with this cement also. Attach a muslin or canvas stocking 4 X 24 inches (10 X 60 cm.) to the small can with a drawstring. Feeding is accomplished through suction from an aspirator consisting of a l/&ch (6-mm.) glass T into which compressed air is conducted through a l/S-inch (3-mm.) tube and nozzle to the intersection of the arms of the T. The outlet end of this aspirator is connected to the inlet tube of the assembled air separator with a short rubber tube. The material to be treated is carried by the air stream to the annular space just within the large can, where the velocity is decreased suffiI
Received January 31,1929.
Self-Emptying Suction Flask for Sugar Determinations‘ Gilbert Pitman FRUITPRODUCTS LABORATORY, UNIVERSITY BERKELEY,CALIF.
OF
CALIFORNIA,
N the Munson and Walker method of determining sugar Icopper difficulty is often experienced in washing the precipitated oxide with alcohol and ether. Ordinarily the ether washings volatilize so rapidly when striking the hot wash water in the flask that they form a pressure great enough t D dislodge the asbestos mat in the Gooch crucible. The following modification in the suction flask has been found useful in overcoming this difficulty. It also permits rapid washing and makes frequent emptying of the flask unnecessary. The principle involved is merely that of drawing the hot wash water from the flask by suction through a glass tube extending to the bottom of the flask. A piece of glass tubing of approximately 4 mm. outside diameter and 2 mm. inside diameter is bent a t an angle of slightly more than 90 degrees and cut so that one end is about 2 em. and the other about 15 em. from the bend. It is cut to fit the flask so that its final position is as shown in the illustration, with the bottom end about 5 mm. from the bottom of the flask. The short end of the tube is fastened to the suction outlet by means of a small rubber stopper t h a t h a s been previously s h a p e d t o m a k e a tight fit and sealed to the flask with clear Duco.’ The stopper is held in place with fine copper wires during drying. These may be dissolved later with nitric acid. Instead of the arrangement described above, an Erlenmeyer flask m a y b e fitted with a two-hole rubber stopper through which a funnel and a suction tube extend to the bottom of the flask. Or the use of the small rubber stopper for the side connection may be avoided by fastening the tube to the suction outlet by means of a glass ring seal. 1 Received
January 29. 1929.
