BOOK REVIEW
A Tale of Two Chemists
Seymour Mauskopf
A World on Fire: A Heretic, an Aristocrat, and the Race to
Discover Oxygen. Joe Jackson. xiv + 414 pp. Viking, 2005. $27.95.
Lavoisier in the Year One: The Birth of a New Science in an Age
of Revolution. Madison Smartt Bell. xiv + 214 pp. Atlas
Books/W. W. Norton and Company, 2005. $22.95.
The story of the chemical revolution that took place at the end of
the 18th century is one of the most compelling in the history of
science. Nearly 60 years ago, this narrative was given particular
dramatic force by James Bryant Conant in a case study titled The
Overthrow of the Phlogiston Theory. In 1962, Conant's
formulation achieved iconic status in Thomas S. Kuhn's seminal work,
The Structure of Scientific Revolutions. Kuhn, like
Conant, shaped his account as a duel between two heroic scientific
protagonists, Joseph Priestley and Antoine Laurent Lavoisier.
The drama was heightened by the fact that Priestley, the apostle of
the phlogiston theory, had discovered a gas that promoted combustion
and respiration far better than ordinary air. He had named it
dephlogisticated air (more on this later). This same
gas, about which Lavoisier had learned from Priestley, became the
centerpiece of Lavoisier's new antiphlogistic theory and
was given a new name by him: le principe oxygine
("acid maker"). The fact that we still call the gas
oxygen and find dephlogisticated air an obsolete
and mystifying name shows clearly who was the victor in this
intellectual battle.
The two books under review here deal with this central episode of
the chemical revolution—and with much more. A World on
Fire, by Joe Jackson, elaborates on both of Conant's heroic
figures, providing additional irony and piquancy by considering
their full biographies. Priestley, the scientifically conservative
phlogistonist, was a flaming radical in virtually all of his other
activities and writings. In contrast, Lavoisier, the revolutionary
scientist, was very much a member of the social and political French
establishment of the ancien régime. The violence and
harassment that Priestley suffered for his political and religious
views, particularly for his support of the French Revolution, drove
him from England to America. At the moment Priestley was leaving for
the New World, Lavoisier was already imprisoned, and during the
Reign of Terror he would forfeit his life for his prior social and
political associations and activities. Madison Smartt Bell's
Lavoisier in the Year One focuses on Lavoisier but
parallels A World on Fire in providing accounts of both his
scientific and his extrascientific pursuits, culminating in his
death by guillotine on May 8, 1794. (The "year one" of the
title refers to the first year of the new revolutionary calendar,
the interval between September 22, 1792, and September 21, 1793.)
Neither of these books is written by a professional historian of
science. Indeed, both authors are, among other things, novelists. In
light of this, let me compliment them at the outset for having
really worked at writing serious historical studies. Each has
developed deep knowledge of and quite exceptional rapport with the
social, cultural and political milieus of the times and places in
which their subjects lived. In the case of Jackson, this is no mean
feat, because he is concerned with three countries (England, France
and the new United States of America). For social and political
context, Bell relies on the magisterial writings of Lavoisier
biographer Jean-Pierre Poirier and, to a degree, on the equally
excellent study of Lavoisier by Arthur Donovan.
Both Jackson and Bell are at their best in detailing the activities
of Priestley and Lavoisier that, strictly speaking, lay outside of
their science. As it happens, I was reading these accounts of
Priestley's travails just as the British government was, in the
weeks after the London underground bombing, instituting draconian
measures against anyone expressing support of Islamic-based
terrorism. What struck me with shattering force was how similar
Priestley's situation in the early 1790s was to that of those
accused or suspected of supporting terrorism today. He was
both a political and a religious radical, and the British
establishment treated him like one.
Lavoisier's life also emerges as being highly pertinent today in
terms of his political and social activities, because he was in many
respects the first major scientist to deploy his expertise—and
more important, his prestige—in the service of the state. He
was, in a phrase, the first modern government scientist. Through my
own work, I am most familiar with his role as the leader of the
French gunpowder service, but that was only one of a multitude of
things he did for his country. Some were done through his position
in the Académie des Sciences; others arose from his work as a
fermier général, a collector of state
taxes. As is well known, there was a reciprocity, even a synergy,
between Lavoisier the tax collector and economist, and Lavoisier the
quantitative "book-keeper" of chemical reactions. He
brought rectitude and rigor to France's economic
activity—perhaps too much at times, and this came to haunt him
during the revolution. It didn't help that as a power broker in the
Académie des Sciences, Lavoisier had also slighted the
scientific pretensions of future revolutionary leaders such as
Jean-Paul Marat. Marat—and others—remembered.
Priestley and Lavoisier, then, make for vividly contrasting studies
of scientists who lived fully active lives outside the laboratory
during these turbulent times. The nonscientific aspects of the lives
and careers of the two men are dealt with quite brilliantly by both
Bell and Jackson. Indeed, it probably helps that they are novelists;
historical writing (at its best) can be riveting, and there is
probably no better way to master the craft of dramatic narration
than by writing novels.
However, the handling of the scientific activities of Priestley and
Lavoisier is less successful and betrays, in my opinion, the
authors' lack of a fully professional viewpoint, which is not
unexpected, given that they are not historians of science. Jackson's
book is the more egregious in this regard. My principal criticism
has to be couched carefully, because I realize that many readers may
well sympathize with Jackson's and Bell's perspective more than
mine. What I find troubling is the evaluation of the phlogiston
theory, the theory espoused by Priestley and shattered by Lavoisier,
as bad science, as patently erroneous science that would
naturally be repudiated by anyone who paid attention to his or her
senses. Here is Jackson's narrative on Priestley's naming of
"dephlogisticated air":
Yet in the midst of his greatest triumph, he made his
greatest mistake. . . . . . . Despite the existence of his
senses, he was still tangled up in phlogiston: he claimed his
discovery was air somehow stripped of that flammable, mythical
fluid. He'd broken through in the lab, but not in his mind.
Oxygen was not yet oxygen. Joseph stuttered in the
worst way he ever had, and called his new find
"dephlogisticated air."
Perhaps the principal lesson Kuhn taught was the need for the
historian of science to empathize with scientific theories and
practices—with what he called "paradigms"—of
earlier ages. The corollary of such empathy is the realization that
scientific change is not an unambiguous or simple move from error to
truth. Indeed, as Bell realizes, the phlogiston theory was a
powerful means of providing order and guidance for research in many
domains of chemical investigation. It took Lavoisier himself several
years to move from adherence to phlogiston to his new oxygen-based
chemistry. Without denying the power—and yes,
superiority—of Lavoisian chemistry, a true historian of
science would be interested in evaluating the scientific functions,
and virtues, of the phlogiston theory, even though it was overthrown.
In his discussion of the scientific changes taking place in
18th-century chemistry, Bell is actually much more evenhanded and
well informed historically than is Jackson. I was therefore quite
stunned to see him miss the theoretical point of Priestley's
"dephlogisticated air." The name came from a rather
straightforward application of phlogiston theory, in which the
chemical process of combustion was viewed as the release by a
combustible substance of its flammable material (phlogiston) into
the ambient air, as can be "seen" when a log in a
fireplace shoots off flame and leaves a small pile of ash. As new
gases were revealed, some, such as "fixed air"
(CO2), were found to be far less supportive of combustion
(and respiration) than ordinary air; others, like the new gas that
Priestley had discovered, were found to be far more so.
In accord with this understanding of the nature of combustion,
Priestley gave a quite lucid and logical interpretation of the new
gases. Their ability to support combustion and respiration was
more-or-less inversely proportional to the amount of phlogiston they
contained. Gases such as CO2 were already saturated with
phlogiston and could not absorb any more from the combustible
material. However, the new gas Priestley had discovered allowed
combustion to take place with great alacrity; therefore it must be
practically devoid of phlogiston—"dephlogisticated air."
This was the core proposition of Priestley's phlogistic
interpretation. Hence my amazement when I read Bell's
misunderstanding of Priestley's theory:
Theory was not his strongest suit, and he failed to
consider that a loss of phlogiston should not have made the new gas
more hospitable to combustion than atmospheric air, though he had
noticed that it was.
The move to a new chemistry involved, first, the reversal of that
core proposition about the nature of combustion: the demonstration
that something was, in fact, absorbed from the air by the
burning substance. This Lavoisier showed quantitatively in his
famous pedestal experiments with sulfur and phosphorus in 1772.
Second, the nature of the "something" had to be
identified. This, too, was Lavoisier's achievement, but it only
became possible once Priestley had identified the gas that
vigorously supported combustion and told Lavoisier about it.
Third—and most fundamentally—it was necessary to
reconceptualize the chemical natures of the different gases. There
existed no fundamental "pure air" that produced other
types of gases through absorption of phlogiston, as Priestley had
surmised. Rather, gases came in different chemical species, and one
of these was the gas that so vigorously supported combustion and
became united with the combustible. This, too, was Lavoisier's
accomplishment, but, as one could guess, it was hardly just the
result of a new observation.
To me, the most interesting aspect of the history of science is the
study of the laborious processes by which facts and theories that
seem clear and natural to us were hammered out by earlier
scientists. To assume that they should have known better
and have recognized the new theory as "obvious" completely
misses what is most intellectually fascinating about the development
of the sciences.
But, as I have also suggested, the history of science is more than
the study of scientific change; it is also the study of human
beings. This important aspect is dealt with in quite extraordinary
fashion by the authors of these studies of Priestley and Lavoisier.
Both books make for exciting reading.