INDUSTRIAL AND ENGINEERING CHEMISTRY
190
factory than thermometers, particularly at low distillation rates. Asbestos insulation of both stills was necessary. The crude oil is fed to the atmospheric still, which serves to preheat the oils for vacuum flashing and removes the asoline and water. When operation is started, about 1 liter quart) of crude is charged to this still and gradually heated t o 232.22’ C. (450’ F,). Crude i s then added continuously, but slowly, through a separatory funnel to the hot charge. With this arrangement, no bumping or foaming occurs, and it is possible to maintain a higher rate of distillation. The hot bottoms from the topping still are drawn into the vacuum still, being sprayed into it at a high velocity. When operated strictly as a flash unit, there is no difficulty with foaming and entrainment as in ordinary vacuum distillation. If flashing does not remove enough material, a small amount of heat can be applied, making the one flask serve as both a flash chamber and a distillation unit.
TABLEI.
RERUNOF FRACTIONS TO DESIREDGRAVITY
8
Although no attempt was made to obtain sharp cuts of the lighter materials, these could be secured by including fractionating columns in the setup. No difficulty has been experienced in running different crudes. The results were equally satisfactory upon East Texas, Smackover, Midcontinent, Pennsylvania, and California oils. By careful control, fractions of any gravity desired may be obtained. Table I shows the results of rerunning a Texas gas oil fraction to obtain experimental cracking stock, and the separation of a Texas lubricating distillate from heavy residuum.
VOL. 9,NO. 4
Charge Atmos herio unit distihte Vacuumunitdistillate Vacuum unit residue
Texas Gas Oil Fraction Absolute Temp. Pressure
Texas Residue Fraction Absolute Temp. Pressure
‘A. P . I . 32.2
‘A.P.I. 23.0
35.0 31.1 28.8
OF,
..
505 310
..
Mm.
..
754 7
..
26:2
OF.
Mm.
.,
..
580 485
752
20.0
..
6
..
The apparatus has been found useful for the vacuum distillation of lubricating distillate t o lubricating oils, using the atmospheric still as a preheater for the flashing chamber, and in solvent-extraction work for removing and recovering solvents from the raffinate and extract. Here the first still was used to recover most of the solvent and the oil was then flashed into the second still to remove the last traces.
Literature Cited (1) Podbielniak, W. J., IND.ENG.CHEM.,Anal. Ed., 5, 135 (1933). (2) Scheumann, W. W., and Stewart, J. F., Refiner Natural Gasoline Mfr., 14,276 (1935). R E C ~ I V EJanuary D 22, 1937. Contribution 226. Department of Chemistry, Kansas State College,
Vessels for the Storage of Gases and Liquids JULIUS SENDROY, JR., Hospital of The Rockefeller Institute for Medical Research, New York, N. Y.
T
HE vessels described have been satisfactorily used for
some time in this laboratory to serve several purposes
in the gas analysis of gases and liquids. Requiring no expert glass blowing, they are easily constructed from readily available, inexpensive materials. These advantages, coupled with their sturdiness, flexibility, and convenience in manipulation, constitute an improvement over the accessories hitherto employed for the same purposes.
Storage of Air-Free Reagents over Mercury
It has been found that the reagents or solutions used for manometric analyses (6, 7) can best be kept air-free over mercury. For such storage a modified Hempel pipet (6) and similar vessels have been used. Of late, there have been designed in other laboratories several different one-piece types of vessels, necessitating more or less expert glass blowing in their construction, which have had as their purpose avoidance of the ruinous contact of alkali or other reagents with the glass control stopcock. Such models have been described by Guest and Holmes (6) and by Holmes (3). The author’s design of a vessel suitable for the storage of reagents, particularly strongly alkaline ones, air-free or otherwise, and possessing the advantages outlined above, is shown in Figure 1, model 1. A is a 236-c~. (8-ounce) “Hygeia” wide-mouthed nursing into which the container arts are set, for convenience in handling or for setting on any f a t surface. Into A are set B, a 30-cc. (or 60-cc.) separatory funnel, and C, a bulb of convenient capacity from 15 to 75 cc., with an external capillar tube ending, a, of 1.5--.internal diameter, bent as indicated, 4- to 5-mm. tube ending, b. The ends of B and C are connected at the bottom with a piece of thick capillary rubber tubing, T . The bulb and funnel are held in place in A by a two-hole No. 10 rubber stopper, R, shortened by 5 mm. at the bottom. The stopper is slit from the outside to each of the holes, so that C and B may be easily slipped into place after the connection at r has been made. The
‘ bottle
anis
usual rubber adapter tip, E,is put on the end of the capillary, a If necessary for greater stability, the bottom of this and the other models may be weighted with either mercury or lead shot, W . The reagent is made air-free by extraction‘in the manometric apparatus, and is transferred to the storage vessel under pressure, as described by Peters and Van Slyke (4, p. 235). If, for convenience, B is of only 30-cc. capacity, and more than this volume of reagent is to be stored in C, the mercury overflow from B may be caught by the insertion of the stopper and tube, X , into the neck of B. The rubber tube, T,may lead to a beaker or other container. By means of wiring around the indented rim of the bottle, A , this and the other models may be temporarily suspended at a convenient height, so that in any transfer of reagent or gas the operator need only use one hand to hold the capillary, a, firmly in the cup of the Van Slyke apparatus. At all times, when not actually delivering reagent, the veseel should stand with tip E immersed in a small beaker of mercury. This and models 2 and 3 are more easily taken apart, for cleaning or change of reagent, if the vessel is first emptied of most of the mercury it may contain. These vessels may be used for any reagent not affected by mercury, and contact between reagent and control stopcock is avoided. Air-free N sodium hydroxide, observed in such a vessel over a period of 18 days, showed an increase in air content of only 4.1 mm. measured in the Van Slyke apparatus a t the 0.5-cc. volume, for a 5-cc. sample of solution.
Storage of Blood Samples and Other GasContaining Solutions Model 2, Figure 1, is the same as model 1, with a change in the form of the external capillary ending, a, t o permit withdrawal of portions of solutions into a pipet, through the rubber connection, 0. Tube al (the ending of which is like that of a, model 1) in this model is removable, and is used only to transfer liquid to the vessel. This model may be used in place of the more cumbersome type of apparatus (1, Figure 3, p. 129) for the storage of gas-containing liquids, particularly blood as drawn. It is also useful for the storage of air-free reagents which must be delivered quantitatively, as in method C of Van Slyke and Sendroy (8, pp. 521,525) for the determination of small amounts of nitrogen in oxygen or carbon dioxide.
191
ANALYTICAL EDITION
APRIL 15, 1937
t A r Model 3
Model 1
FIGURE 1. STORAGE VESSELS Model 1 for storage of air-free reagents Model 2: for storage of b!ood samples apd pther gas-containing solutions Model 3, for storage of either gases or 11qulds
In this, and in the other models of this series, it may more often be necessary to transfer a solution into the vessel under negative pressure, as in the separation of serum from cells, a procedure effected in other systems by the lowering of a free leveling bulb corresponding to B. The same result may be attained by the use of the stopper and bent tube, X,inserted into the neck of B. With the thick-walled capillary rubber tubing, T,a connection is made to a 250-cc. suction flask to which suction may be a p plied. In case neither house nor water pump vacuum is available when the sample is transferred to C, as at the bedside, a small Becton and Dickinson “Potain” aspirating syringe, connected to the suction flask, has been found most satisfactory. A few strokes of the plunger are made, the syringe is laid down, and the o erator is then free for the manipulations involved in the transkr of material to the container. Depending on the length of glass tubing, X , in the rubber stopper in the neck of B , the mercury in B may be kept a t any convenient level, with overflow running into the suction flask, while the sample is taken into C. Later, when mercury is needed for dis lacement, it may be added to B through a small funnel. If B is farge enough, there need be no tube X and vacuum may be applied to B directly.
Storage of Either Gases or Liquids By another change in the external ending of bulb C, model 3 serves as a very convenient container to take the place of the usual types of gas-sampling tubes (4, Chapter 111). The threeway, 120°, Y-form capillary stopcock, Y,provides for washing gas through from a2 (the ending of which is like that of a, model 1) t o asor vice versa, and then storage of the sample in C, through limb a. (The 120’ stopcock is not an item usually carried in stock by supply houses, but can readily be obtained on order. The usual three-way, 90°, T-form capillary stopcock will do as well, and has been satisfactorily used by the author.
However, one must be very careful in its manipulation, SO as to avoid the dangers of simultaneous double connections. When used for gas analysis only, any capillary three-way stopcook may be used in place of X.) Gas samples may bc taken into the Haldane gas-analysis apparatus by a lass connection from limb as, or into the manometric apparatus y direct insertion of limb at into the cup of the chamber. Obviously, this vessel may also be used as is model 2, for the storage of blood or other as-containing liquids. If a dry anticoagulant be placed in blood may be drawn directly into this vessel by the attachment of needle to a short length of rubber tubing connected to limb a? The initial flow is wasted through e,and then the sample 1s drawn in through a, under slight negative pressure.
f
8,
Model 3 may also be used for the storage of nonalkaline, air-free reagents. For alkaline reagents, however, model 1 is much t o be preferred.
Literature Cited (1) Austin, J. H., Cullen, G. E., Hastings, A. B., McLean, F. C., Peters, J. P., and Van Slyke, D. D., S. B i d . Chem., 54, 121 (1922). (2) Guest, G. M., and Holmes, F. E., Ibid., 110,781 (1935). (3) Holmes, F.E., Ibid., 113,411 (1936). (4) Peters, J. P., and Van Slyke, D. D., “Quantitative Clinical Chemistry.Vol. 11. Methods,” Baltimore, Williams & Wilkins Co., 1932. (5) Van Slyke, D.D., S. B i d . Chem., 73,121 (1927). (6) Van Slyke, D.D., and Hiller, A.,Ibid., 78, 807 (1928). (7) Van Slyke, D. D., and Neill, J. M., Ibid., 61,523 (1924). (8) Van Slyke, D. D., and Sendroy, J., Jr., Ibid., 95,509 (1932). RECBIVBD February 2, 1937.
