NOVEMBER 15, 1935
ANALYTICAL EDITION
/7GNEr ,,-CIRCULAR
FAN
(t
Pwor
TABLE
I
FIGURE3
Sheet-metal tin disks 2.5 inches in diameter were cut and punched at the center with an ordinary center punch, care being used not to puncture the metal, to serve as the socket of a pivot bearing. Six radial cuts 1 inch deep were made in the edge with tin shears, and the segments were bent to serve as fan blades. These fans were then balanced on the pivots and the unit was placed inside the desiccator, so that the fans when in place just cleared the side. The fan may be lifted off the pivot and laid aside for removal or insertion of the sample dishes. With this type of pivot the fans rotated freely and were induced to rotate by magnets passing near the outside of t,he desiccator and on a level with
44 3
the fan. The electromagnetic flux permeating the glass induced the fan to rotate, and no mechanical connection to the fan was necessary. The motive Dower was furnished bv a series of motor car magneto-magnets mounted on a circular platform, on a Boston Gear Company show window display unit of 48 to 1 ratio. An 1800-r. p. m., 0.125-h. p. electric motor was belted directly to the gear unit. A 2.5-foot diameter platform furnished ample space for 15 desiccators placed in a circle concentric with the platform and just outside the circle created by the passage of the magnets. The magnets were passed at the rate of 8 feet per minute and the more freely moving fans rotated at approximately 200 revolutions per minute.
Literature Cited (1) Lindsay, D. C., International Critical Tables, Vol. 2, pp. 321-6 (1927). (2) Wilson, R. E., J. IND. EXG.CHEM.,13, 326-31 (1921). (3) Wilson, R. E., and Fuva, T., Ibid., 14, 913-18 (1922). RECEIVED September 17, 1935. Agricultural Engineering.
Contribution No. 66, Department of
A Molecular Still WILLIAM H. STRAIN A N D WILLARD M. ALLEN The University of Rochester, School of Medicine and Dentistry, Rochester, N. Y .
I
N THE course of the purification of the corpus luteum
hormone, progestin (S), i t was found necessary to subject the highly purified concentrate to distillation in a molecular still. Since the described devices designed for use with small quantities were not entirely satisfactory for this purpose, a new type of apparatus modeled after the molecular still of
Yl FIGURE1
Carothers and Hill (1) was designed. The still has the advantage that, in addition to being readily charged and cleaned, the temperature of distillation may be simply controlled. The still (Figure 1) was constructed from tm-o pieces of oldstyle, flanged Pyrex pipe, 15 X 5 cm., the final dimensions being given in the diagram. After the apparatus was fabri-
cated i t was annealed and the surfaces ground for highvacuum work. The still was heated by means of a small oil bath placed around the well of the apparatus. I n operation the thick oil to be distilled is dissolved in a small amount of ether and transferred b y pipet to the well, The solvent is removed by cautious warming or by an air jet and the last traces by evacuation-hst with a water pump and then with an oil pump. During this preliminary evacuation the condensing part of the apparatus is not used, the upper end being closed with a rubber stopper. Finally, when i t is apparent that easily volatile substances have been removed, the stopper is replaced by the condenser, and the apparatus, including the trap, is attached to the intake of a mercury vapor pump. With the joints well greased and the mercury pump trapped with solid carbon dioxide, a vacuum of 0.0002 mm. is attained in a very short time, providing no distillation is taking place. By slowly heating the oil bath surrounding the well the distilling temperature is reached without any visible boiling and a waxy substance soon collects on the pestle from which it can be removed b y immersion in benzene or other suitable solvent. A well of the size used will accommodate from 1 to 2 grams without difficulty. T h e detailed set-up of the high-vacuum apparatus and the technic of operation were essentially those described by Hickman and Sanford ( 2 ) . This same apparatus has been used for the purification of a, number of other products of biological origin and appears to be adapted to a large variety of conditions.
Literature Cited (1) Carothers, W. H., and Hili, J. W., J . Am. Chera. Soc., 54, 1557 (1932). (2) Hickman, K. C. D., and Sanford, C. R., J. Phys. Chem., 37, 637 (1930). (3) Wintersteiner, O., and Allen, W. M.,J . BioT. Chem., 107, 321 (1934). RECEIVED August 29, 193.5.
