Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure

Dupraw, W. A.

Gahn, R. F.

Graab, J. W.

Maple, W. E.

Rosenblum, L.

English

NASA Technical Reports Server

July 1966	 Brief 66-10296 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Apparatus Enables Accurate Determination of Alkali Oxides in Alkali Metals 
Sample Container 
Hot-Wire Cut Off
Mechanism 
Waste Tray 
To Mercury Reservoir 
Ball Check Valve 
Glass Covered Magnetic Bar 
The problem: 
To devise an analytical test apparatus for determin-
ing the alkali oxide content of an alkali metal. The ap-
paratus must prevent the inadvertent introduction of 
oxygen and moisture into the system during the sam-
pling and analytical procedure. A reliable method for 
determining the oxygen content of alkali metals is im-
portant because alkali oxide impurities in alkali metals
Extruder 
To Vacuum Pump 
Valve
To Vacuum Pump 
0-Ring Joint 
- Extraction Tube 
- Exit Valve 
To Vacuum Pump 
- Receiving Flask 
(even below 20 ppm in some cases), which have been 
used as heat transfer media, can promote corrosion 
attack on the walls of the heat transfer equipment. 
The solution: 
An evacuated apparatus in which the alkali metal 
is separated from the oxide by amalgamation with 
mercury.
(continued overleal) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000295 2020-03-11T17:39:37+00:00Z
How it's done: 
The apparatus consists of two major sections: an al-
kali metal extruder and an extraction section, con-
nected by 0-ring joints. 
The sample container is a stainless steel tube 6 3/4-
inches long by 5/16-inch inside diameter. It is vacuum 
filled with liquid alkali metal to be analyzed, capped, 
and stored under vacuum until used. For analyses, the 
sample tube is mounted in the extruder section of the 
apparatus. To perform an analysis, the entire appa-
ratus is evacuated to a pressure between 2 x 10- 5 and 
4 x 10-6 torr. A small portion of the alkali metal is 
extruded from the sample tube, cut with the hot wire, 
and discarded into the waste tray. The analytical 
sample is then extruded, cut off, and dropped into the 
glass extraction tube. The extruder is valved off from 
the extraction tube and the ball check valve is seated 
in place to confine the subsequent amalgamation of 
the sample. A quantity of triple distilled mercury is 
then admitted to the extraction tube. After the amal-
gamation of the sample is completed, manipulation of 
a glass covered magnetic bar within the extraction 
tube removes all film from the tube walls. By means of 
an exit valve on the restricted end of the extraction 
tube, the amalgam is slowly admitted into the receiv-
ing flask. The exit valve is closed, and a second quan-
tity (approximately 15 ml) of mercury is admitted to 
the extraction tube and the magnetic bar manipulation 
is repeated. The wash mercury is removed as before. 
A total of five similar washes is made to ensure com-
plete removal of the alkali metal amalgam; 700 to 900 
grams of mercury are used in all. 
The extraction portion of the system (below the 
0-ring) is brought to atmospheric pressure and re-
moved together with the amalgam receiving flask. 
The alkali metal is extracted from the amalgam in 
the receiving flask with boiled distilled water. The hy-
droxide solution thus produced is titrated with stand-
ard acid to determine the weight of the alkali metal in 
the sample.
Any alkali oxide in the extraction tube is washed 
out with boiled distilled water. The resulting hydrox-
ide solution is titrated with 0.005 N acid, using a mi-
croburette, to determine the amount of alkali metal 
oxide in the sample. 
Notes: 
I. This system was tested extensively to determine the 
oxygen content of samples of potassium. The re-
sults obtained showed good precision, independ-
ently of the time that the chemical components 
remained in the extraction system (up to 24 hours, 
the longest time studied). 
2. The apparatus incorporates the following advan-
tages over the standard Pepkowitz—Judd apparatus: 
(1) the entire system is maintained under a high 
vacuum, (2) the volume of the amalgamation reac-
tion tube is small, (3) a ball check valve is used to 
contain the amalgamation reaction, (4) greased and 
waxed joints are eliminated, and (5) replicate sam-
ples are taken from a single sample tube. 
3. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B66-10296 
Patent status: 
This invention is owned by NASA, and a patent ap-

plication has been filed. Royalty free, nonexclusive 
licenses for its commercial use will be granted by
NASA. Inquiries concerning license rights should be

made to NASA, Code GP, Washington, D. C. 20546. 
Source: L. Rosenblum, W. A. Dupraw, 
R. F. Gahn, J. W. Graab, and W. E. Maple

(Lewis-256) 
Brief-66-10296	 Category 03


Apparatus enables accurate determination of alkali oxides in alkali metals

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