phosphorus. This increase in weight comes from a prodigious quantity of air which is fixed
during the combustion and which combines with the vapours. This discovery, which I have
established by experiments which I regard as decisive, made me think that what is observed
in the combustion of sulphur and phosphorus could well happen with regard to all bodies
which gain weight by combustion and calcination, and I became convinced that the weight
increase of metallic calces is related to the same cause. Experiment has completely confirmed my conjectures. I performed the reduction of litharge in closed vessels with Hales’
apparatus, and I observed that at the moment of change from calx to metal a considerable
quantity of air is released and that it makes up a volume at least one thousand times greater
than the litharge used. This discovery seemed to me one of the most interesting that has
been made since Stahl, and because it is difficult not to let one’s friends in conversation
catch a glimpse of something that might put them on the road to the truth, I deemed it
necessary to make this deposition into the hands of the Academy’s secretary, while waiting
till I make public my experiments. [67].
It would, however, take Lavoisier several years to perfect his theories. After some
preliminary experiments, Lavoisier’s sealed note was opened on May 5, 1773, and in
January 1774, he published his book Opuscules physiques et chimiques, where he
reported some preliminary results. A copy of this book was sent to Scheele in
Uppsala, and must therefore also have reached Bergman. In October 1774, Lavoisier
got two important pieces of information. He both received Scheele’s letter and met
Priestley in the company of Lord Shelburne. Priestley told Lavoisier about his
discovery of oxygen at a dinner, and the following month Lavoisier performed
experiments on heating of mercury oxide. From his laboratory notes, it is clear that
he still in March 1775 believed that the gas formed on heating mercury oxide was
carbon dioxide.
On April 26, however, he read a paper at a meeting of the Académie des
Sciences—the so-called Easter memoire. It is important to note that the original
version was printed in Rozier’s Observatisons sur la Physique [68], while the
official version in Mémoires de l’Académie Royale des Sciences [69] was not
actually printed until 1778. The final version was updated by Lavoisier and may
give the impression that Lavoisier’s theories were developed about 3 years earlier
than was actually the case. In the original version, Lavoisier regarded air as a
substance mixed with carbon dioxide and water vapour. Priestley criticised this
theory [70]. In 1777, after many experiments, Lavoisier realised that air was not a
substance, and in the final version of the Easter memoire, he stated that a burning
substance reacts with the purest part of the air. The name oxygine (Greek όnύf,
acid, and cemήf, former) was introduced in September 1777, when Lavoisier
believed he could prove oxygen to be a constituent in all acids [71]. In his book
Traité élémentaire de chimie, published in 1789 and regarded as the first modern
textbook in chemistry, Lavoisier gave a clear description of oxygen as an element
that reacts with burning substances. This book appeared in its first English edition,
Elements of Chemistry, only a year later.
Lavoisier’s theories were not immediately accepted, but gained more and more
supporters during the years that followed. Some chemists, like Priestley, would stay
true to the phlogiston theory well into the nineteenth century. Due to his
involvement in a tax collecting firm, Ferme générale, Lavoisier was arrested during
21.8 Lavoisier and the Chemical Revolution
297
during the combustion and which combines with the vapours. This discovery, which I have
established by experiments which I regard as decisive, made me think that what is observed
in the combustion of sulphur and phosphorus could well happen with regard to all bodies
which gain weight by combustion and calcination, and I became convinced that the weight
increase of metallic calces is related to the same cause. Experiment has completely confirmed my conjectures. I performed the reduction of litharge in closed vessels with Hales’
apparatus, and I observed that at the moment of change from calx to metal a considerable
quantity of air is released and that it makes up a volume at least one thousand times greater
than the litharge used. This discovery seemed to me one of the most interesting that has
been made since Stahl, and because it is difficult not to let one’s friends in conversation
catch a glimpse of something that might put them on the road to the truth, I deemed it
necessary to make this deposition into the hands of the Academy’s secretary, while waiting
till I make public my experiments. [67].
It would, however, take Lavoisier several years to perfect his theories. After some
preliminary experiments, Lavoisier’s sealed note was opened on May 5, 1773, and in
January 1774, he published his book Opuscules physiques et chimiques, where he
reported some preliminary results. A copy of this book was sent to Scheele in
Uppsala, and must therefore also have reached Bergman. In October 1774, Lavoisier
got two important pieces of information. He both received Scheele’s letter and met
Priestley in the company of Lord Shelburne. Priestley told Lavoisier about his
discovery of oxygen at a dinner, and the following month Lavoisier performed
experiments on heating of mercury oxide. From his laboratory notes, it is clear that
he still in March 1775 believed that the gas formed on heating mercury oxide was
carbon dioxide.
On April 26, however, he read a paper at a meeting of the Académie des
Sciences—the so-called Easter memoire. It is important to note that the original
version was printed in Rozier’s Observatisons sur la Physique [68], while the
official version in Mémoires de l’Académie Royale des Sciences [69] was not
actually printed until 1778. The final version was updated by Lavoisier and may
give the impression that Lavoisier’s theories were developed about 3 years earlier
than was actually the case. In the original version, Lavoisier regarded air as a
substance mixed with carbon dioxide and water vapour. Priestley criticised this
theory [70]. In 1777, after many experiments, Lavoisier realised that air was not a
substance, and in the final version of the Easter memoire, he stated that a burning
substance reacts with the purest part of the air. The name oxygine (Greek όnύf,
acid, and cemήf, former) was introduced in September 1777, when Lavoisier
believed he could prove oxygen to be a constituent in all acids [71]. In his book
Traité élémentaire de chimie, published in 1789 and regarded as the first modern
textbook in chemistry, Lavoisier gave a clear description of oxygen as an element
that reacts with burning substances. This book appeared in its first English edition,
Elements of Chemistry, only a year later.
Lavoisier’s theories were not immediately accepted, but gained more and more
supporters during the years that followed. Some chemists, like Priestley, would stay
true to the phlogiston theory well into the nineteenth century. Due to his
involvement in a tax collecting firm, Ferme générale, Lavoisier was arrested during
21.8 Lavoisier and the Chemical Revolution
297