Rediscovery of the Elements: Aluminum Page: 1 of 6
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Rediscovery of the Elements
James L. Marshall, Beta Eta 1971
Virginia R. Marshall, Beta Eta 2003
Department of Chemistry, University of
North Texas, Denton, TX 76203-5070,
Believe It or Not
Figure 1. This Robert L. Ripley's cartoon headlines
the possibility of simultaneous discovery in the
sciences and reminds us that discovery will occur
"when the time is ripe."Heroult's discovery is doc-
umented in his French patent application dated
April 23, 1886, Hall's in a letter dated February
24, 1886, which established priority in the U.S.
Patent Office. In the original cartoon published in
the (London) Sunday Express, June 12, 1938, Hall
and Hiroult were heralded "The Aluminium
Twins."(Photo, courtesy of Ripley Entertainment
DE o nhagen
Thury-Harcourt a Paris 500 km
Figure 2. During the 18th and 19th centuries, the
important research on aluminum was done by
scientists in Denmark, Germany, and France, and
in the United States (Ohio-not shown).
Aluminum, even though it is the most
common metal in the earth's crust, was
not isolated in elemental form until the
early 1800s, and its commercial produc-
tion did not commence until half a centu-
ry later with the development of the Hall-
Hiroult process (see Figure 1).
Alum (potassium aluminum sulfate,
A1K(SO4)2.12H20) has been used as a mor-
dant (fixer of dyes) for centuries.' Ancient
mines of alum were located at volcanic sites
where the alum crystallized out from
hydrothermal waters rich in sulfates produced
by the oxidation of extruded sulfur. By the 17th
century, alum was commonly used in the paper
industry, and also as an antiseptic, medicine,
and a"preserver of organic bodies" (embalmer).
Stahl, whom we met earlier in the HEXAGON2
as the proponent of phlogiston, believed it con-
tained lime (calcium). He showed that alum
could be leached from clay, but he could not
prepare it by reacting lime with various acids.
There continued to be much confusion in the
scientific world regarding chalk (calcium car-
bonate), gypsum (calcium sulfate), Epsom salts
(magnesium sulfate), alum, and other "earths"
until the middle of the 1700s.
Figure 3. This bust of Marggraf stood on the out-
side wall of the Berlin Academy, beside that of his
student, Franz Carl Achard (1753-1 821), at the
Berlin Academy at Dorotheenstrasse 10 (N 520
31.16, E 13023.68; then known as"Letzten
StraJfe'). Accompanying legends on the statues
lauded both Marggraf and Acha rd for their dis-
covery and commercial application of sucrose in
the sugar beet. The entire building was destroyed
in the Second World War The site is now a vacant
lot in back of the Humboldt University.
The earliest definitive work on alum (Figure
2) was done in 1754 by Andreas Sigismund
Marggraf (1709-1782) of Berlin1 (Figure 3), who
distinguished the respective earths of alum and
lime3 When he reacted lime with oil of vitriol
(sulfuric acid), he obtained only selenite (a
transparent form of calcium sulfate). He dis-
solved alum in alkali and precipitated "Alun-
Erde" ("earth of alum," aluminum hydroxide).
He then dissolved this earth in nitric acid and
showed that calcium compounds (e.g., lime)
could not be generated. By very carefully
adding the correct amount of oil of vitriol and
TH E 062@ w
C1MHAL ol&o AND PL h0W4ToF1RNcE
On THE 23 RDof TE SAME M0N 1H~E SVI YAR em6
AT THE AGE OF 23 - EACH MAmIrDEPENDmLY
AND 1N COMPLETE IGNORANCE OF EACH OTHER,
(Now Known es the HALLHERJ PROCESS)-AND
THe 80TH DIWTESAM1E YEAR -
K02006 Ripley Entertainment Inc.
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Marshall, James L., 1940- & Marshall, Virginia R. Rediscovery of the Elements: Aluminum, article, Summer 2006; Indianapolis, Indiana. (digital.library.unt.edu/ark:/67531/metadc111212/m1/1/: accessed July 27, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Arts and Sciences.