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Book Review Vom Radiothor zur Uranspaltung. Eine wissenschaftliche Selbstbiographie. (Reprint of the 1st Edition). By O. Hahn

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BOOK R E V I E W S
Vom Radiothor zur Uranspaltung. Eine wissenschaftliche
Selbstbiographie.(Reprint of the 1st Edition). By 0.Hahn.
F. Vieweg & Sohn, Braunschweig/Wiesbaden 1988. xvi,
160 pp., hard cover, DM 78.00. -ISBN 3-528-08413-8
Of the many books on the life and work of Otto Hahn this
one, published in 1962 in his 84th year, was the first, and it
is probably the only one written entirely by him. The re-publication of the book on the fiftieth anniversary of the discovery of nuclear fission is therefore greatly to be welcomed. The
description of it as a “reprint” is to be interpreted literally,
as Otto Hahn’s text has remained completely unaltered. Even
the few printing errors have not been corrected. Also unaltered are the three appendices, which are facsimiles of papers
on nuclear fission: Otto Hahn and Fritz Strassmann’s “second” paper in the 1939 volume of Naturwissenschaften reporting the famous radioactive indicator experiments, and
two review articles from the Abhandlungen der PreuBischen
Akademie der Wissenschaften for 1941 and 1944. The illustrations section has, however, been revised; the editor
Dietrich Hahn, grandson of the author, has approximately
doubled their number to 40. Also new are a preface by the
editor and an introduction by Kurt Starke, who worked with
Hahn from 1935 to 1940 as a graduate student and scientific
collaborator.
The book is first and foremost a scientific autobiography;
personal details are only included in special circumstances.
However, it is not written in a scientific style with the customary self-effacement on the part of the author. On the
contrary, Hahn’s temperament and his style of working become clearly apparent after only a few pages. In a relaxed
and unpretentious way he describes his early youth, student
days and teaching days with much anecdotal backgroundhis famous “cock tales”+ven when the point of the story is
at his expense. A lucky accident-and in this book luck is
often mentioned-had the effect of diverting him from a
planned career as an industrial organic chemist towards radioactivity instead. Having gone to London in order to learn
English, he achieved his first scientific success in 1904 in
William Ramsey’s laboratory, in a way that was typical of
him: while separating radium from barium salts by fractional crystallization the mother liquor was unexpectedly found
to be still weakly radioactive afterwards. This “residue effect” led him to discover a new member of the natural radioactive decay series, radiothorium (thorium-228). This
earned him a place in Ernest Rutherfords laboratory in
Montreal, and eventually, in 1906, in that of Emil Fischer in
the chemistry department of Berlin University. There he
made his next important discovery, that of mesothorium-1
Angeu. Chem. Inr. Ed. Engl. 29 (1990) No. 2
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(radium-228), which was soon greatly in demand for radiotherapy as an alternative to the considerably more expensive
radium. However, the greatest discovery escaped him: despite the fact that he had made more unsuccessful attempts
than Frederick Soddy at separating closely similar “radioelements” (p. 46), it was Sod4 rather than Hahn who arrived
at the concept of isotopes which was the key to this problem.
In 1907 he gained his Habilitation under Fischer. In the
same year there began the collaboration with the physicist
Lise Meitner, which was excellent both scientifically and
from a personal standpoint. Hahn had access to nearly all the
known radioelements, and they now undertook a systematic
study of all their radiations. While once more investigating a
“residue effect”, they discovered radioactive recoil. Lise
Meitner gradually made a reputation for herself in this environment, in which the attitude towards women w d S one of
disapproval. In 1912 the two moved to the new Kaiser-Wilhelm-Institut fur Chemie, which was another stroke of luck,
since Otto Hahn had scarcely any prospects for a university
career in his field of work; he was regarded by chemists as a
physicist, whereas to physicists he was a chemist. He turned
his attention to the radioactivity of the elements potassium
and rubidium; out of this work was developed, twenty years
later, the rubidium-strontium method for determining the
age of geological samples. The laborious studies of radioactive decay series, interrupted by Hahn’s and Meitner’s war
service, reached their high point in 1918with the discovery of
element 91, protactinium. Once again it was a “residue effect” in protactinium-234 which led to Hahn’s discovery in
1922 of the first example of nuclear isomerism, although it
was not fully understood until many years later.
The paths of Otto Hahn and Lise Meitner now diverge.
Although Hahn continued to provide support for Lise Meitner’s detailed studies of radioactive emissions, which eventually led Wolfgang Pauli to the discovery of the neutrino,
Hahn himself now turned, with the help of his now numerous
collaborators, to applied radiochemistry. He used radioactive isotopes to investigate chemical problems such as the
chemistry of substances in extremely small quantities, orby using his “emanation method”-the modification of surfaces, the structures of solids, and solid-state chemical reactions. In 1933 he gave a series of lectures at Cornell
University, Ithaca, which subsequently appeared in the form
of a book. Worried about political developments and about
the fate of Jewish friends and colleagues, he cut short his stay
there. In January 1935 he courageously gave the keynote
address at the remarkable memorial service for Fritz Haber.
From a scientific point of view this was the least productive
period in Hahn’s life. At that time, as Kurf Starke describes
it, the younger research collaborators felt that nothing more
remained to be discovered in radiochemistry.
However, that verdict was premature. In the spring of
1934 Enrico Fermi and his collaborators reported the discovery of the first transuranic element, number 93, resulting
from the irradiation of uranium with neutrons. Nevertheless
there were objections to this: might not the element be protactinium instead? Lise Meitner and Otto Hahn, acknowledged authorities on matters related to protactinium, resumed their work together, and were soon joined by the
young Fritz Strassmann. The results became more and more
complex; it emerged that there were two decay series of
transuranic elements which extended as far as element 96.
For thorium too several isomeric decay series were found,
but in this case they corresponded to known elements, begin-
Verlag.~gesellschaf!mbH, 0-6940 Weinheim. 1990
0570-0833/9OIO202-0219S 02SOjO
219
ning with radium. In the summer of 1938 events took a
dramatic turn: Lise Meitner was forced to flee the country,
while IrPne Curie and Paul Savitch in Paris discovered a
transuranic element whose chemical properties certainly did
not fit into the scheme of the Berlin team. Hahn and Strassmann at first identified this activity as due to radium, but
after further work aimed at rigorously verifying this surprising result they revised their verdict and identified bariumthus uranium fission was discovered. A hesitant first communication was followed soon by the second paper which is
reprinted here, providing certain confirmation through a
whole series of brilliant radiochemical indicator experiments. In the fractional crystallization of barium salts the
activity obtained from uranium became uniformly distributed through all the fractions, whereas natural radium added
at the same time became selectively concentrated in the top
fractions. These fractionations were the same as those which
Hahn had performed in his student days in Ramsey’s laboratory, and the most important indicator for radium was
mesothorium-I , Hahn’s own discovery. In this remarkable
way the nearly sixty-year-old scientist had thus returned to
the starting-point of his researches.
Otto Hahn does not discuss the further developments leading to the atomic bomb, since the team at the Kaiser-Wilhelm-Institut was not involved in this aspect. Nor do we
learn anything about the German “uranium club”. The political tensions in the Institute receive equally little attention.
The fact that Hahn was under extraordinary pressure at that
time can be best only be inferred between the lines: the anecdotal detail no longer appears, the tone becomes more serious. He summarizes the work of chemically unravelling the
complex mixture of fission products, and the results thus
obtained. He relates with satisfaction how, using primitive
resources, they identified 100 products, and speculates about
which of the fission products might have been mistaken for
“transuranics”. From the pre-war research only uranium239 remains as having been unambiguously identified as
such by Hahn, Meitner and Strassmann. However, its decay
product, element 93, proved very difficult to find in Berlin.
The final chapter is brief: a few sentences about Hahn’s
internment in England, the Nobel Prize for Chemistry in
1944, the presidency of the Max-Planck-Gesellschaft.
The illustrations section has grown in size compared with
the first edition, as Dietrich Hahn has chosen to include some
photographs relevant to the period. Some of these are of
great interest, such as the “Sofabild” of 1920 (p. 88), showing Lise Meitner and Otto Hahn with their circle of friendsHerta Sponer. Einstein, Grotrian, Westphal,the Francks, Otto von Baeyer, Peter Pringsheim, Haber, Hertz. What a
remarkable elite was gathered there!-and what happened
to them? However, some changes in the selection of photographs will be a cause of regret. For example, Kaiser Wilhelm
the second arriving in uniform at the formal opening of the
Chemie-Institut, followed by Adolf von Harnack and Emil
Fischer wearing top-hats, is so typical of the period that one
would have liked to see this photograph (1 st Edition, p. 61)
still included.
Kurt Starke evokes the atmosphere in Hahn’s research
institute from the viewpoint of a young member of the team.
One gains an impression of the rather simple way in which
the laboratory was furnished, and of the strict safety precautions against radioactive contamination; one senses the cordial atmosphere, but also the clear division between the leader’s immediate team and the younger members. For the
latter, the first news of the successful experiments carried out
around the turn of the year in 1938/39 came when the work
was published.
220
0 VCH
Verlagsgesellschafi mbH, 0-6940 Weinhelm. 1990
Otto Hahn’s book ends with a backward look, in which he
represents his scientific career as a succession of lucky events.
This probably has something to do with his Rhineland-Hessen temperament, which always looks at the positive side of
a situation. The fact that there were also low points, such as
the propagation over several years of the transuranic elements, which eventually faded away, is not apparent from
the book, but only from the correspondence between Hahn
and Meitner. Nevertheless, Hahn and Strassmann were able
to correct their error by making a discovery of even greater
importance. Of course there are many questions that remain
unanswered: what prompted Hahn and Strassmann to carry
out the apparently superfluous radioactive indicator experiments?-how were tasks distributed, and what was the nature of the interactions, in the Hahn-Meitner-Strassmann
team?-and many more. However, one can learn a great deal
from this book without necessarily wishing to go into radioactive phenomena in greater depth: concerning, for example, how science advances not by logical steps in an orderly sequence, but by circuitous and often strange routes; how
the most experienced research groups can continue for years
with experiments and theories which miss the point; how, on
the other hand, they can be set on the right track by a lucky
stroke of intuition; and how a scientist may return, decades
later, to something which he worked on as a novice. One
therefore hopes that this book will be read especially by
young scientists. Some will look here for some comments on
nuclear energy by the man who has often been called the
“father of the atomic era”. Otto Hahn devotes only half a
sentence in the foreword to this topic-it seems that he did
not see himself in that role.
Giinter Herrmann [NB 989 IE]
Institut fur Kernchemie
der Universitat Mainz (FRG)
Nitrosamines. Toxicology and Microbiology. (Ellis Horwood
Series in Food Science and Technology). Edited by
M. .
IHill. VCH Verlagsgesellschaft, Weinheim/VCH
Publishers, New York/Ellis Horwood, Chichester 1988.
169 pp., hardcover, DM 180.0GISBN 3-527-26708-5/
0-89573-605-0; ISSN 0930-3332
Many nitrosamines are highly toxic, carcinogenic and genetically harmful. Owing to their organ-specific carcinogenic
properties and their occurrence in foodstuffs, cosmetics and
tobacco smoke, and in work-places, together with the fact
that they can be formed endogenously in the human body,
there has been widespread interest in this class of compounds
in experimental cancer research and in environmental health
studies.
The main emphasis in this book is on the importance of
nitrosamines in relation to human health. The eight chapters
by various authors cover methods for detecting N-nitroso
compounds in biological samples, the chemistry of N-nitrosylation reactions, mechanisms of endogenous N-nitrosylation, the occurrence of N-nitroso compounds in the human
environment, the toxicology of N-nitroso compounds, and
the role of these compounds in inducing human cancers. A
further chapter suggests ways in which the risks of nitrosamine-induced cancers can be minimized.
Impressive characteristics of the book are the systematic
and well-disciplined structure of the individual chapters, and
the detailed references to original publications (extending up
to 1988 in some parts). The book deals with all important
aspects of the topics treated, and the reader is enabled to
0570-0833190j0202-0220$02.SOjO
Angen. Chem. lni Ed. Engl. 29 (1990) No. 2
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