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A Source Book in Chemistry, 1400-1900
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General SummaryThe formulation of the phlogiston theory, first conceived in principle by Johann Becher, was finally due to his pupil, Georg Ernst Stahl. He accepted the doctrine that combustible substances contain an ignitable matter, the terra pinguis of Becher. To this Stahl gave the name phlogiston (derived from [figure table] to inflame). Most of the chemists of the eighteenth century were believers in the phlogiston theory, which, though erroneous, still provided a basis for the many experiments that contributed to the birth of modern chemistry under the influence of Antoine Lavoisier. Stahl was one of the first to formulate a rational system of chemistry on a structure of experimental observations.To Stahl, metals were compounds containing phlogiston in combination with metallic oxides (calces); on ignition the phlogiston was freed from the metal, leaving the oxide behind. When the oxide was heated with a substance rich in phlogiston, such as charcoal, the calx again took up phlogiston and regenerated the metal. Phlogiston was a definite substance, the same in all its combinations. To explain the gain in weight during calcination of metals, the concept of negative weight was introduced.The first definition of phlogiston appeared in Stahl’s "Zymotechnia funda-mentalis," first published in 1697. Stahl speaks of his phlogiston in the following selection.Stahl wrote several treatises on chemistry, of which "Fundamenta chymiae" is the best known, since it had an important influence on chemists of the period. It is here that Stahl’s often-quoted definition of chemistry is to be found.In his discussion of the composition of substances, Stahl divides all matter into several classes, depending on their chemical nature. He uses the usual four elements and three principles. The combination of the original principles into simple compounds he terms mixts. A further union of mixts forms compounds, whereas a miscellaneous group of substances are designated aggregates. The following selection illustrates his treatment of the subject.
Georg Ernst Stahl
Definition of Chemistry
PRELIMINARIES
1. Universal chemistry is the Art of resolving mixt, compound, or aggregate Bodies into their Principles; and of composing such Bodies from those Principles.
2. It has for its Subject all the mix’d, compound, and aggregate Bodies that are resolvable and combinable; and Resolution and Combination, or Destruction and Generation, for its Object.
3. Its Means in general are either remote or immediate: that is, either Instruments or the Operations themselves.
4. Its End is either philosophical and theoretical; or medicinal, mechanical, economical, and practical.
5. Its efficient Cause is the Chemist.
THE COMPOSITION OF SUBSTANCES
THE STRUCTURE OF SIMPLE, MIX’D, COMPOUND AND AGGREGATE MATTER
1. As mix’d, compound, and aggregate Bodies are, according to our Definition, the Subject of Chemistry, ’tis necessary that we here consider their chemical Structure.
2. All natural Bodies arc either simple or compounded: the simple do not consist of physical parts; but the compounded do. The simple are Principles, or the first material causes of Mixts; and the compounded, according to the difference of their mixture, are either mix’d, compound or aggregate: mix’d, if composed merely of Principles; compound, if formed of Mixts into any determinable single thing; and aggregate, when several such things form any other entire parcel of matter, whatsoever it be.
3. A Principle is defined, à priori, that in mix’d matter, which first existed; and à posteriori, that into which it is at last resolved.
4. Both these definitions are exact, if we allow of a pure, natural resolution: but as this is not easily obtainable from the Chemistry of these days, and so can hardly be come at by Art, a difference, at present, prevails between the physical and chemical Principles of mix’d Bodies.
5. Those are called physical Principles whereof a Mixt is really composed, but they are not hitherto settled: for the four Peripatetical Elements, according to their vulgar acceptation, do not deserve this title. And those are usually termed chemical Principles, into which all Bodies are found reducible by the chemical operations hitherto known.
6. These chemical Principles are called Salt, Sulphur, and Mercury; the analogy being taken from Minerals: or, Salt, Oil, and Spirit; to which Dr. Willis adds Phlegm and Earth; but improperly, since Phlegm is comprehended under Spirit: for inflammAble Spirits cannot be here meant; these consisting manifestly of Water, Oil and Salt, as we shall see hereafter.
7. But as the four Peripatetic Elements, howsoever understood, cannot have place, if supposed specifically the same in all Subjects; so neither can the Chemical Principles: for no-one has hitherto pretended to shew that these Principles are specifically the same in all Bodies. But if consider’d only as to their generical qualities, they may be allow’d in Compounds.
8. We say particularly in Compounds, because all the darkness and disputes about Principles arise from a neglect of that real distinction between oriqinal and secondary Mixts, or Mixts consisting of Principles and Bodies compounded of Mixts. Whilst these two are confounded, and supposed to be resolved by an operation that is contrary to Nature, the common chemical Principles of vegetables, animals and minerals are produced, and prove in reality artificial Mixts: but when Compounds are separated by bare resolution, without the least combination, their Principles are natural Mixts.
9. By justly distinguishing between Mixts and Compounds, without directly undertaking to exhibit the first Principles of the latter, we may easily settle this affair. Helmont and Becher have attempted it; the former taking Water for the first and only material Principle of all things; and the other, Water and Earth; but distinguishing the Earth into three kinds.
1 "Zymotechnia fundamentalis seu Fermentationis Theoria generalis, qua nobilis-simae hujus artis et partis chymiae, utilissimae ac subtillissimae, causae et effectus in genere, ex ipsis mechanico-physicis principiis, summo studio eruuntur . . . ," Halle, 1697.
This work also appears in the "Opuscuhim Chymico-Physico-Medicum" of Stahl, from which the extracts are, in part, taken: "Opusculum Chymico-Physico-Medicum, seu Schediasmatum a Pluribus Annis Variis Occasionibus In Publicum Emissorum Nunc Quadantenus Etiam Auctorum Et Deficientibus Passim Exemplaribus In Unum Volumen Jam Collectorum, Fasciculus Publicae Luci Redditus, Praemissa Prae-fationis Loco Authoris Epistola Ad Tit. Dn, Michaelem Alberti D. & Prof. Publ. Extraordinarium. Editonem hanc adcuratem. Halae Magdeburgicae, Typis & Impen-sis Orphantrophei. Anno 1715."
2 "Opusculum Chymico-Physico-Medicum . . . ," pp. 144–145. This is a portion of Cap. XII of the "Zymotechnia."
6Ibid., p. 3.
Contents:
Chicago:
Georg Ernst Stahl, "The Composition of Substances," A Source Book in Chemistry, 1400-1900 in A Source Book in Chemistry, 1400-1900, ed. Henry M. Leicester and Herbert S. Klickstein (New York: McGraw-Hill Book Company, Inc., 1952), 58–63. Original Sources, accessed July 1, 2025, http://www.originalsources.com/Document.aspx?DocID=8EUGU7MPXWA3WV5.
MLA:
Stahl, Georg Ernst. "The Composition of Substances." A Source Book in Chemistry, 1400-1900, in A Source Book in Chemistry, 1400-1900, edited by Henry M. Leicester and Herbert S. Klickstein, New York, McGraw-Hill Book Company, Inc., 1952, pp. 58–63. Original Sources. 1 Jul. 2025. http://www.originalsources.com/Document.aspx?DocID=8EUGU7MPXWA3WV5.
Harvard:
Stahl, GE, 'The Composition of Substances' in A Source Book in Chemistry, 1400-1900. cited in 1952, A Source Book in Chemistry, 1400-1900, ed. , McGraw-Hill Book Company, Inc., New York, pp.58–63. Original Sources, retrieved 1 July 2025, from http://www.originalsources.com/Document.aspx?DocID=8EUGU7MPXWA3WV5.
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