Chemistry Reference
In-Depth Information
obtained the requested minerals from P. A. Kochubei and he read in the accompa-
nying letter: “I am sending you according to your request the following minerals:
(1) eschynite, (2) ilmenite, and (3) perovskite. The first and last minerals I have
managed to obtain from stock with great difficulty—and this took place not without
damage to the best specimens, but I will not complain if the results you will obtain
justify your expectations.”
73
The reason why Mendeleev asked for some specimens of rutile, ilmenite and
zirconium should be clear by now. But why was he in need of orthite, cerite, and
eschynite? Both cerite and eschynite are rich in cerium (and to a lesser degree also
in lanthanum and yttrium). The mineral orthite, on the other hand, is not only
abundant in cerium, it also contains substantial amounts of the other rare-earth
elements. Obviously, Mendeleev was not only planning to discover the unknown
eka-silicon, he also hoped to perform some experimental research on the rare earths
in order to resolve their problematic accommodation.
As soon as he had received his mineral supplies from the Mining Institute
and the Russian Technical Society, Dmitrii Ivanovich enthusiastically embarked
upon his quest for eka-silicon and he also initiated his investigations of the rare-
earth elements—trying to prove the validity of his
homologous accommodation
methodology
. As Gordin stated, “he even refused a post at Moscow University on
the grounds that he did not want to give up his current research on the rare earths.”
74
Mendeleev pasted two periodic tables in his laboratory notebooks and he used them
as a newfangled and powerful paper tool to guide his modern chemical research
(Fig.
11.7
).
75
As can be seen from the figure, Mendeleev had scribbled some of the
rare-earth elements in thick red characters in the third group of his natural system.
According to Nathan Brooks, “Mendeleev spent considerable time trying to
separate the four known rare-earth elements over the course of about one year,
but he only met with failure. The difficulty was compounded because two of these
rare earths (didym and erbium) later turned out to be mixtures of several elements
and not pure elements.”
76
As a consequence “Mendeleev
s patience with this
research agenda ran out quickly”.
77
On the twentieth of December 1871, after
scribbling no more than 67 pages in his lab topic, Mendeleev decided to abandon
all research on the rare-earth metals, and he set off on a gas project in search of the
luminiferous ether. “On this date, on this page,” said Gordin, “we can pinpoint
the death of
all
research by Mendeleev on the periodic system. Gas expansion, not
elemental discovery, became his goal.”
78
At the upper left hand corner of his short
form system, above hydrogen, Dmitrii Ivanovich had scrawled: “The ether is lighter
than all of them by a million times” (Fig.
11.7
).
79
'
73
Loc. cit.
74
Gordin (2004), op. cit., p. 43. (note 51)
75
Loc. cit.
76
Brooks (2002), op. cit., p. 138. (note 10)
77
Gordin (2004), op. cit, p. 50. (note 51)
78
Loc. cit.
79
Ibid., p. 52.
