NOVEMBER 15, 1938
ANALYTICAL EDITION
by giving it a preliminary draw to start the taper and then continuing as described above.
645
uses is illustrated in Figure 3, a. When sealing a section of the tubing, A, into an apparatus an air-tight, flexible joint may be made a t B with a single turn of rubber tape which is butted together and pinched with the finger tips as in b. After the seal a t C is made, the tape is torn off by grasping the tab, D . Most irregular joints may be sealed by stretching the tape as it is wrapped around the joint. Several turns will seal a stopper in an irregular tube. A convenient temporary repair in a vacuum system may be made by using a technic described by DuMond and Youtz (1) and attributed to Lauritsen and Crane. The organic chemist should find it useful for numberless purposes.
By this method a 10-mm. joint may be shaped and ground in about 15 minutes of a c t u a l w o r k i n g time.
Rubber Tape
A very convenient material, both in FIGURE 3. USE OF RUBBER TAPE glass blowing and in the general laboratory, is ordinary electricians’ rubber tape. It is extremely cohesive, being made of uncured rubber stock. One of its
Literature Cited (1) DuMond, J.
W.,and Youtz, J. P., Rev. Sci. Instruments, 8, 301
(1937). (2) Harris, J J., and Schumacher, E. E., J. 174-7 (1923).
IXD. ENQ.CHEM.,15,
RECEIVEDJune 23, 1938. Paper So. 14 Journal Series, General Mills Inc., Research Laboratories.
Filling Closed-End Mercury Manometers JESSE WERNER, Columbia University, New York, N. Y
A
NURIBER of methods have been proposed for filling closed-end mercury manometers without boiling out the mercury inside the manometer (1, 2, 3, 5 ) . However, these methods, although avoiding the difficulties and inconveniences encountered in boiling out the mercury inside the manometer, are either complex in setup or give impure mercury because of contact with grease. I n order to circumvent these difficulties, various manometers, such as that of Zimmerli (6), have been devised which do not have to be filled by boiling out, but in general they suffer from being large and unwieldy or difficult for the inexperienced glass blower to make. By means of a modification of the method proposed by Malmberg and Nicholas for periodically boiling out entrapped gases from the oil in an oil manometer (4), closed-end mercury manometers may be very easily filled. The method is extremely simple and may be used by beginning students on soft-glass manometers, or may be modified to take care of filling more complex manometers, where an all-glass system is desired. Its greatest use probably lies in filling simple manometers for general organic work. The only equipment necessary is a good Hyvac pump and a bulb (or a wide tube constricted a t both ends) large enough to hold in its lower portion all the mercury necessary to fill the U-tube, as shown in Figure 1. The bulb containing the mercury, which should be dry and pure, is attached with pressure tubing to the open end of the manometer and to the Hyvac pump. When the maximum vacuum is attained, the air is driven out from between the glass and the mercury by shaking and tapping. The manometer and mercury may then be gently heated to drive out all volatile matter. When all the air is out, the mercury is carefully poured down into the U-tube and air is let in slowly to fill the manometer. This method may be modified for more complicated types of mercury manometers. For a manometer containing a stopcock the above method may be used or else a bulb may be sealed on between the stopcock and the U-tube, as shown in Figure 2. The mercury in the bulb may then be heated gently to expel the air, the U-tube filled, and the bulb pulled off in
the torch. This arrangement prevents the mercury from coming into contact with stopcock grease. I n the case of a sloping manometer ( I ) , a bulb may be sealed on temporarily and the outfit attached to a mercury diffusion pump. The manometer is then baked out while the mercury is heated, and the mercury is then distilled into the cooled manometer.
Literature Cited (1) Burton, I X D . ENG.CHEM., FIGURE 2 Anal. Ed., 9, 335 (1937). (2) Cameron, Ibid., 5 , 419 (1933). (3) Doja, J . Chem. Education, 10, 574 (1933). (4) Malmberg and Kicholas, Rev. Sci. Instruments, 3, 440 (1932) (5) Weatheril!, J. Am. Chem. SOC.,47, 1947 (1925). (6) Zimmerli, ISD.ENQ.CHEX, ilnal. Ed., 10, 283 (1938). RECEIVED August 10, 1938.
