An Improved Distilling Column Head AMOS TURK AND ALFRED MATUSZAK Ohio State University, Columbus, Ohio

ANY types of column heads commonly used for total 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 afore- mentioned disadvantages.

A -

2 3 1 w r n . ~

B-

D4 C

I L

I --:I I I cm.

1 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 com- bined in one simple rigid unit. The condenser reflux is trapped around the rim of the drop counter at D, and sufficient conden- sate is thereby deflected to the stopcock, E.

This system of arrangement is such that the entire appara- tus is a short direct continuation of the column shaft itself, and thus any 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 with- out dismantling; the use of a test-tube brush will usually be

sufficient. If some water accumulates in the cooled parts of the tube during distillation, the thermometer can be tempo- rarily removed and the tube wiped out with cotton suspended on a wire; this can be done within a few seconds without in- terrupting operation. The glass-blowing construction is also of a simple and strain-free nature.

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 down- ward. In 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.

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 uni- formly satisfactory service.

Rapid Detection of Nickel in Allov Steel

J

T. H. WILLIAMS Bowser-Morner Testing Laboratories, Dayton, Ohio

HE need for a rapid and nondestructive method for differ- T 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 dimethylglyox- ime as the indicating reagent. Of prime importance in the test procedure is the use of an acid mixture consisting of sul- furic, 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 de- gree 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 re- quirements, 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 hydro- chloric and nitric used individually produced intensely colored solutions which made impossible any di-cernment of color indi- cation. Phosphoric acid, suggested by Griffin ( 4 ) , showed no sign of reaction with any of the types of alloy steels that were investigated.

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 di- methylglyoxime.

Alpha-benaildioxime wm tried as an indicating reagent, but the results obtained were unreliable and too easily mis- interpreted.

2.

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