INDUSTRIAL A S D ENGINEERING CHEMISTRY
34
VOL. 10, NO. 1
various grades of kerosene are rated in the same order and are tested with equal precision.
of opinions and comments from members of the Inspection Laboratories at Richmond and El Segundo.
Acknowledgment
Literature Cited
Acknowledgment is hereby made of the valuable assistance of P. S. Williams of the Manufacturing Engineering Department in developing various mechanical improvements, and
(1) Terry, J. B.,and Field, Edward, 293 (1936).
IXD. ESG CHEY.,Anal. Ed., 8,
RECEIVED September 23, 1937.
Fractionating Device for Vacuum Distillations E V A 1 NOON,IN, Columbia L-niversity, 4ew- York, N. Y.
S
EVERAL devices have been described for removing fractions of distillate without interrupting the course of a distillation under reduced pressure. Thorne ( 5 ) originated a n apparatus for this purpose which employed three stopcocks, and many modifications and elaborations have since appeared. Sattler ( 4 ) designed an arrangement to eliminate some of the difficulties inherent in the earlier types. ,4simple device due to Sason (3) is also used, wherein but two stopcocks are required. However, the distillation must be interrupted vihile the receiving flask is being evacuated, and this is often undesirable. I n some modifications the distillate is collected in a receiver having two chambers, one of which can be restored to atmospheric pressure and the fraction of distillate withdrawn without disturbing the vacuum in the other chamber. A compact model of this type employing four stopcocks was worked out by Delaby and Charonnet ( 2 ) . One of the most convenient of these de-
Tyj
The stopcock plug is hollow, with two 2-mm. tubes sealed in diagonally, in the manner of an ordinary three-way stopcock. Three 3-mm. holes are drilled through the wall at the smaller end of the plug to communimte with outlets T and G . One hole is drilled in line with the sealed-in bores and communicates with G when the plug is in the position illustrated. The other two holes are drilled at an angle of 90" to the first. One of them coincides with outlet T when the plug is in the position shown; the other is directly opposite. Tube T enters the shell of the stopcock at the rear and at a right angle to the plane of the drawing. The upper end of this tube enters the upper part of the receiver near the connection for the condenser. The condenser tube should be so arranged that liquid cannot enter tube T. Tube L is bent to the rear and the end expanded for rubber tubing connection. The receiver is attached to the condenser at A , a receiving flask is placed at B, and the pump is connected at C. The stopcock is then turned to the position shown. The entire system can be evacuated, since ports in the hollow plug communicate with T and G. The distillation is allowed to proceed, and when it is desired to collect another fraction the stopcock is turned 180°, whereupon air or an inert gas is admitted through tube L to the receiving flask. The distillation continues into receiver R, the vacuum being maintained through tube T and the port in the hollow stopcock. A new receiving flask is placed at B , and upon turning the stopcock 90' in the proper direction the receiving flask will be evacuated through tube G, while the rest of the system is momentarily disconnected from the pump. The stopcock is then turned 90" farther and the original position is resumed, the accumulated distillate running into the receiving flask. The receiver, R, may be graduated if desired.
It is impossible to let air into the system accidentally in excess of the amount contained in the receiving flask if the latter is in place. This is also t'rue of the apparatus as originally designed by Bogert, but unfortunately in many modifications which have appeared this provision has been neglected. I n some designs the connection for a n inert gas is through a stopcock with a "tail" plug, and the tension of the rubber tubing may push it out, I n the device described this is avoided and the plug is held in place by atmospheric pressure. Because of the compact construction the device is not, as fragile as it might appear.
Literature Cited
B
v
FIGURE 1.
vices is that designed by Bogert ( 1 ) 71-hich has a graduat,ed receiver so that fractions of known volume can be collected, and utilizes three stopcocks. I n the device to be described the functions of from two to four taps are combined in a single stopcock, which is advant,ageous in collecting fractions rapidly.
DIaGRAM O F .kPPARhTWS
IXD. ESG. CHEY.,7, 785 (1915). (2) Delaby and Charonnet, BuZl. SOC. chim., 43, 1287 (1928). (3) Nason. IXD.EXQ.CHEM.,15, 1188 (1923). (4j Sattler, I h i d . , 17, 583 (1925). (5) Thorne, Ber., 16, 1327 (1893). (1) Eogert, J.
RECEIVED October 4, 1937.
