An Improved Distilling Column Head AMOS TURK AND ALFRED MATUSZAK Ohio State University, Columbus, Ohio
ANY types of column heads commonly used for total
sufficient. If some water accumulates in the cooled parts of the tube during distillation, the thermometer can be temporarily removed and the tube wiped out with cotton suspended on a wire; this can be done within a few seconds without interrupting operation. The glass-blowing construction is also of a simple and strain-free nature.
reflux-variable take-off distillation, although efficient in operation, possess disadvantages due to inconvenient bulkiness of construction, difficulty in glass blowing, ease of breakage, and inaccessibility to cleaning. In this laboratory a column head has been developed which has all the operating advantages of the more elaborate designs, without the aforementioned disadvantages.
For making the reflux counter, a short section of tubing of the same diameter as that used for the main shaft of the column head is cut and its ends are beveled. The upper end is prepared for sealing by flanging it and then bending the lip slightly downward. I n this way a sloping gutter is formed around the tube at D when the seal is made. After sealing in the reflux counter, the side tube for the take-off valve may be attached.
I A-
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I1 I I cm.
231wrn.~
B-
D4 C
The column head is pictured in the accompanying diagram. The thermometer well, condenser, reflux counter, and variable take-off valve are all constructed around a single tube, A , which extends vertically from the column shaft. The thermometer, suspended as shown, comes in direct contact with the va ors from the column; the arrangement is such that there are no fead spaces that would materially disturb equilibrium conditions. When an Anschutz thermometer is used, the uncooled portion, B, provides for complete immersion of the mercury stem in the hot vapor. The drop counter, C, and take-off devices are combined in one simple rigid unit. The condenser reflux is trapped around the rim of the drop counter at D, and sufficient condensate is thereby deflected t o the stopcock, E.
This type of column head has been in use on about thirty columns of various types in this laboratory for 2 years, with compounds boiling from 36" to 168" C., and has given uniformly satisfactory service.
Rapid Detection of Nickel in Allov Steel J
T. H. WILLIAMS Bowser-Morner Testing Laboratories, Dayton, Ohio
T
HE need for a rapid and nondestructive method for differ-
entiating steel gears containing 1 to 2 per cent of nickel from gears made of plain carbon and molybdenum-alloy steels resulted in a spot-test procedure using dimethylglyoxime as the indicating reagent. Of prime importance in the test procedure is the use of an acid mixture consisting of sulfuric, phosphoric, nitric, and citric acids, which eliminates the need for preliminary separations of interfering ions and the grievances generally associated therewith. Previously described spot-test procedures (1, 2, 3, 6, 6, 7), although using dimethylglyoxime as the indicating reagent, have never given to the conditions of initial reaction the degree of importance that is demanded in a test of this type. I n order to obtain unmistakable results, the acid solution of the elements of the steel alloy had to fulfill two principal requirements, which are met by the acid mixture described below. 1. The solution obtained in the initial reaction of acid and steel must be colorless, in order to prevent the possibility of masking the color indication of nickel. Acids such as hydrochloric and nitric used individually produced intensely colored solutions which made impossible any di-cernment of color indication. Phosphoric acid, suggested by Griffin ( 4 ) , showed no sign of reaction with any of the types of alloy steels that were investigated. 2. The reaction of ferrous ions and dimethylglyoxime must be suppressed, This reaction is characterized by a deep red coloration (b),which is easily mistaken for the nickel salt of dimethylglyoxime.
This system of arrangement is such that the entire apparatus is a short direct continuation of the column shaft itself, and thus a n y strains or breakage danger caused by bulkiness or dispersed distribution of weight of the parts are eliminated. Furthermore, the apparatus can be cleaned very easily without dismantling; the use of a test-tube brush will usually be
Alpha-benaildioxime wm tried as an indicating reagent, but the results obtained were unreliable and too easily misinterpreted. 72
January 15, 1942
ANALYTICAL EDITION
Reagents and Procedure
13
Summary
Acid Mixture: 25 ml. of distilled water; 10 ml. of sulfuric acid, specific gravity 1.84; 10 ml. of nitric acid, specific gravity 1.42; 10 ml. of phosphoric acid, 85 per cent; and 10 grams of citric acid crystals. and Potassium Hydroxide: 30 grams of Potassium 90 ml. of distilled water. Dimethylglyoxime, 1 per cent, in isopropanol. Test Papers: Strips of filter paper dipped in a solution contnining 10 grams of citric acid, 25 ml.. of distilled water, and 10 nil. of 1 per cent dimethylglyoxime in isopropanol. Strips are thoroughly dried and can be kept in stoppered bottles. One drop of the acid mixture is placed on the steel and allowed to react for 15 to 30 seconds. This solution is then absorbed on a paper test strip and 2 to 3 drops of potassium hydroxide Solution nre Doured over the spot.
If nickel is present an unmistakable red coloration will appear, its intensity increasing with a n increase in percentage of nickel present. The absence of nickel is indicated by an almost total ab"lor that Of "lor On the test strip* Any might occur will be distinctly brown [Fe(OH)J and cannot lie confused with the red nickel glyoxime precipitate.
The rapid nondestructive SPot-test Procedure described is specific and positive in the identification of nickel in nickelbearing alloy steels. Positive tests were obtained on a series of typical heat-resistant and corrosion-resistant steels ranging in nickel content from 0.50 t o 35 per cent No questionable or interfering color reactions from elements other than nickel have been observed.
Literature Cited (1) Boyd, Thos., with Degering, E. F., and dhteve, R. S . ,ISD. ENG CHEM..ANAL.ED..10. 606 11938). (2) Clarke, B. L., and Hermance, H . W,', I b i d . , 9, 292 (193'7). (3) Ibid,, 591 (1938). (4) Griffin, R. c.,"Technical Methods Analysis", 2nd ed., p. 145. New York, McGraw-Hill Book Co., 192'7. ( 5 ) Lange, N. A., Forker, G. M., and Burington, R . S., "Handbook of Chemistry", p. 716, Sandusky, Ohio, Handbook Publishera. (6) Smith, Lothrop, and West, P. W., ISD.ENG.CHEX, h x a ~ED., . 13, 271 (1941). (7) Yagoda, Herman, I b i d . , 9, 79 (1937').
Attachment for Pipets for Precise Transfer of Dangerous Fluids WILLIAM R. THOMPSON Division of Laboratories and Research, New York State Department of Health, Alhanj-, N. 1..
DEVICE illustrated in Figure 1has been found useful in the laboratories of this division not only for dangerous chemicals, such as combustion fluids, b u t for precise work Jl-ith bacterial and virus suspensions and has some advantages over other available devices in simplicity of construction and convenience. I t consists of three essential parts. The first is a suitably sized glass tube constricted at one end, T , to a minute opening, with a wide opening a t the other end, &, and a small vent, T', in the side. The second is a short piece of heavy pressure tubing placed a t T for attachment to the pipet, P. The third is a rubber bulb, B, with holes a t o posite ends fitted around the grass tube with V inside-a single-holed bulb may be bored, stretched over a stopper-borer inserted through the first hole, and bored upon a piece of cardboard or wood till a small second hole is neatly cut, which should be placed next to the pressure tube at T for added strength. The glass part, preferably Pyrex, may be made as follows: Cut a convenient length of tubing, about 5 mm. in outside diameter for small bulbs, 10 ml. or less. Attach a large bulb (about 50 ml., capable of reducing pressure about one-tenth atmoqphere) at one end and rotate the other in a flame, hot enough for fusing, but allow contraction to leave a small hole a t the end. Test its size after removal from the flame, by squeezing the bulb and noting the speed of refllingFIQURE1 about 1 ml. per second or less
Q
should be satisfactory. The slou er this IS, the greater the control in later use. Then heat a small spot on the side for piercing in the usual manner, but blow out by means of the attached bulb. Firepolish this opening to form the vent, V. This may be made almost as small as that a t T , if desired, by reheating and gently dlowing compression-e. g., letting the tube bend slightly around the flame a t the pierce hole and later straightening it. Use of a small vent at B or a small bulb, B , promotes precise control of outflow but a compromise must be made to give satisfactory facility 'in filling. At the time it is made, V may be tested aa was the first vent a t T . In use, pipet P is inserted into the pressure tube to butt against the glass tube a t 2". To fl1 the pipet, the bulb is compressed with second finger and thumb, the index finger is placed over &, the bulb is released, and the thumb is transferred to the rubber tube a t T opposite the other fingers. When the fluid has risen slightly above the initial mark, the index finger is taken from Q momentarily to stop upward flow and returned to restrict downward flow, as in ordinary use of a pipet. Blow-out technique may be used subsequently by closing Q and compressing the bulb as required. For use tvith combustion fluid, as in the Van Slyke-Folch (1) technique, a glass bell may be attached a t T around the rubber tube (as shown in dotted lines in Fi ure l ) ,and the pipet may be left attached to the safety filler, aniiinserted in a glass tube with closed bottom (test-tube form) of suitable size to permit the glass bell to rest upon and cover the top, suspending the pipet abovf the bottom or any collected fluid. The tube may slope about 45 from horizontal. This provides protection from dust in intervals between use. It is convenient also to use a filler with stopcock pipets, and to leave one attached to any pipet used frequently by different workers. The symmetrical form of the filler permits its rotation with the attached pipet in use-e. g., to facilitate reading, to start flow, etc. However, with large bulbs (50-ml. or greater capacity) it is sometimes preferable to use a T-joint instead of the vent at V and attach a single-holed bulb to the side tube.
Literature Cited (1) Van Slyke, D. D., and Folch, J., (1940).
J. E M . Chem., 136, 609-41
