An All-Glass Laboratory Still. G. E. Mallory and R. F. Love,
ing in the bulb and in an ordinary distillation the boiling proceeds very smoothlj rt of the tube from tho The upamxc it to act as an efficient still head t o tl trap and reflux secuon. The tube can be cleaned by boiling water in the flask and immersing the end of the condenser tube in a beaker of wator or cleaning fluid. When the boiling is stopped, the liquid is drawn by suction through the tube, thereby cloaning it
Alcohol Tay Unit, B u r ~ s uof Internal Revenue, S m Francisco, Calif. ordinary laboratory still consisting of boiling flask, conTneeting . tube, and condenser, joined by rubber stoppers, has NE
the disadvantage that the rubber may be affected by the vr~popors produced in the distillation process. Such action may cause contamination of the distillate and it hardens and shrinks the rubber so that tight connections are not always maintained and vapor may be lost through leakage. To obviate these difficulties, allglass stills have been devised in which the two rubber stoppers have been replaced by glass joints; while they are better than the older type, it is rather difficult to adjust the spparatus so that the two glass joints make tight connections, and unequal pressure causes one of the joints to become loose with resultant loss of vapor. The still described here has only one glass joint, the usual connecting tube is eliminated, and one tube extends from the flask through the condenser jacket to the receiver. The separate jacket is attached to the tube by Figure 1 rubber or threaded connections.
Absorption Apparatus for Hydrogen Chloride. Max H. Hubiteher, Resoaseh Laborat,ory, Ex-Lax, h e . , Brooklyn, N. Y. using running water are customarily employed for the water-soluble 1 (2nd ed.), 97 (1941); Allen, C. F. H., Ibid., 2, 4 (1943)1. However, where it is desired to observe the beginning or the end of the development, of hydrogen chloridc, mother type of absorption apparatus has shown great ut,ility and convenience, without the disadvantage of running water. The trap was designed to absorb up to 4 moles of hydrogen chloride developed in synthetic preparative work such &s Friedel-Crait,s reactions, halogenations, and similar pFOCe88eS. RAPS
Tabsorption of hydrogen chloride or other e s e s [Johnson, J . R., Org. Syntheses,Coll. Vol.
As used in this laboratory. laboratory, the tube is 13 mm. in outside diameter, the long arm is 76 70 em. long, and the short arm is 14 cm. long. The length of tube hetween arms is 21 cm. The bulb is 45 mm. in outside diameter. A T joint 29/42 is used. Dimensions can be varied to suit any mod. The supply catdogs do not list the tubes but those described (Figure 1) were furnished by Ace Glass, Incorporated, Vindxnd, N. J. The condenser is held bv .; e sinele clamp, the j a m of w h i c h a r e covered with rubber, or better with woven asbestos sleevcs. and which are ciosed just t i g h t l y enough to prevent the tube from s l i p p i n g . This arrangement psrmits s u f f i c i c n t flexibility to prtvcnt breakage and when the flask is connected or d i s connected, the c o n d e n s e r 1s moved up or down in the clamp, thus avoiding strain on Figure 2 thc tube. ~~
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llllliilLU CM. Vessel B, whcn charged ait,h 350 ml. of water, will absorb 4 moles of hydrogen chloride. The absorption of the gas in B can be observed by the Schlieren formation. Drying tube A has n sintered-glass disk of coarse porosity and holds granular anhydrous calcium chloride or Drierite. This prevents water vapors from diffusing back into the reaction vessel. Any gas not absorbed in B is forced to pass through the water or sodium bydroride solut,ion contained in absorption vessel C. The inner tube of C has a rclat,ively largo diameter to prevent sucking back of the liquid into B.
Figure 2 shows a bank of 15 stills used in this laboratory. As the framework was already installed, the tubes were designed to fit its dimensions. They have been in use for three years with very little breakage. Even when thick liquids which bumped considerably have been distilled, there have been no breakage and no disconnection of the glass joint. The short tube between tho bulb and the joint idarge enough to keep liquid from collect94
