A
Device to Relieve Bumpy
Take-Off for Recovering Solvent from Rubber Extraction Apparatus
Distillations R. T. HILL AND W. L. JACOBS
WM. E. BOYD, Inspection Board of
United Kingdom and Canada, Nobel, Ontario, Canada
Departments of Anatomy and Physiology, Indiana University, School of Medicine, Bloomington, Ind.
T
0 PREVENT bumping during distillation some mechanism is necessary to disperse the heat applied and to agitate the fluid to be distilled. The device herein described has proved extremely effective. I t s principle is basically the same as that involved in a Cottrell ( 1 ) pump for use in the determination of boiling points of solution. However, the apparatus was devised in the absence of any knowledge of the Cottrell pump. A glass tube is bent in a U-form, with one arm somewhat shorter than the other, inverted, and introduced into the distilhng flask ( A ) . The U-tube should be long enough to extend from the bottom of the flask for a short distance into the neck. Its length thus serves to hold it in the upright position. If for any reason a shorter U-tube is desired, a glass rod may be welded to it to hold it upright ( B ) . The short arm of the U should be just above the level of the fluid in the flask while the long arm should rest on the bottom of the flask directiy above the source of heat. No attempt should be made to have the end of the long arm fit uniformly around its rim on the bottom of the flask, al: though no ill effects from a close fit are anticipated. Obviously it should not fit the bottom of the flask so tightly as to prevent the distilling fluid from passing under it. If a large flask IS used for distilling a large quantity of fluid, two or three U-tubes should be added, the short arm of one of which is just above fluid level at the start of distillation. The short arms of the other U-tubes should be of different lengths, and below fluid level. As t h e fluid reaches the boiling point, the heat will cause fluid and vapor to rise to the top of the tube. Then fluid drops descend in the short arm of the tube by a comd bination of gravity and the force of the applied heat. I n this way agitation is produced and the superheated fluid a t the bottom of the flask is partly carried away. When a series of tubes is used, one or more have their short arms above t h e level of the fluid a t a11 times and as the fluid level drops in the flask, others come in t o play. Some advantage is secured, even though both ends are submersed in the fluid, from the circulation of vapor bubbles and fluid through the inverted U-tube. At times it is an advantage to have the long end of the tube flared slightly in the fashion of a funnel (see diagram). The diameter of the glass tube can vary somewhat; an inside diameter of 2 to 3 mm. has been found effective. Modifications can be adapted to meet many needsparticles in the distilling fluid, viscosity, etc. If the presence of metal in the distilling flask is not objectionable a olished brass or aluminum rod, 3 to 4 mm. in diameter, may d e the place of glass.
I
NSTEAD of allowing solvent (carbon tetrachloride) to boil away after extracting material in the Underwriters, rubber extraction apparatus, the following simple take-off was devised. To a flask of sufficiently widemouth to accommodate the condenser is attached a piece of glass tubing having an outside diameter of a t least 10 cm. and bent in the form illustrated in Figure 1. After extraction has been effected in the extraction flask, A , the condenser,C, israised, theextraction thimble is removed, the bent-arm flask, B, is connected with the extraction flask, using a cork stopper, and the conFigure I denser is placed in the mouth of the bentarm flask. The solvent is then boiled out of the extraction flask and the condensate caught in the bent-arm flask, care being taken to avoid excessive heating or drying of the solute in the extraction flask. Solvent recovery is excellent and residual material in A is in no way contaminated for further chemical treatment.
IL
NEW EQUIPMENT and BOOK REVIEW Fluoride Tester The Harrold fluoride tester, a test instrument devised for rapid analysis of a contaminated atmosphere when hydrofluoric acid, sodium fluorides, or calcium fluorides are present, is announced by the Production Equipment Co., 6432 Cass Ave., Detroit 2, Mich. Developed as an aid to safety engineers for the analysis of welding atmospheres and for use in light metal foundries, the complete test kit weighs less than 5 pounds. The air is drawn past a calibrated test paper, which instantly changes color if fluorides are present. Test papers are guaranteed to be stable for 3 months.
Geiger-Counter Spectrometer A new x-ray instrument, the Geiger-counter spectrometer, was unveiled publicly at the National Metal Congress and Exposition, held October 16 to 20 in Cleveland, Ohio. A product of the North American Philips Co., Inc., New York, it utilizes a Geiger-Miiller tube to measure the intensity and position of interference lines encountered in x-ray diffraction analysis work.
Laboratory Guide in Chemistry. Joseph H.Roe. 192 pages. C. V. Mosby Co., St. Louis,Mo., 1944. Price, $1.00.
Many of the authors’ friends have used the inverted U-tube method to control bumping, and recently its use has spread t o other universitief, and laboratories.
Experiments in this laboratory guide, which is bound in a plastic loose-leaf binding, are designed to accompany the author’s textbook “Principles of Chemistry”, and were incorporated in former editions of the text. Forty exercises are presented, five of them prepared for this edition.
LITERATURE CITED
(1) Cottrell, F. G., J . Am. Chem. Soc., 41, 721 (1919).
122
