4. The lesson from science history
Mixing and combining are intrinsic to chemistry from its very beginnings in Modern Times, when it parted from alchemy during the XVIIth and XVIIIth century, as can be documented from the books of Jean Béguin (Tyrocinium chymicum), Lémery, and Macquer. Already in this early period, there are numerous indications, from the various authors, that they conceptualized chemical species as the union of component particles. The art of the chemist consisted in separating these, using operators such as heat or menstrues (solvents), prior to recombining them in novel ways.
The evidence is widespread. The entry CHYMIE by Gabriel Venel in the Encyclopédie is very clear on this point. The whole chapter in the history of chemistry devoted to the devising of tables of chemical affinities in the 1770s partakes of the same notion of a systematic exploration of the binary interactions of various elements, to use a modern terminology. At that time of the 1770s, one can argue for the existence of an explicit research program to systematically chart the map of such binary compounds. One example makes that point very effectively. This is the book by Baumé: Chymie expérimentale et raisonnée. (Paris, Didot, 1773). It is a systematically organized description of both existing and unknown chemical compounds. The pages of Baumé’s treatise swarm with negative observations such as those quoted below, pointing to an overall view of chemistry as a combinatorial science:
- vol. 2. p. 145 “Borax and Lime Water. The effects both of lime and of lime water on borax are unknown”
- “Borax and Sulfur. The effects of sulfur on borax are also unknown.”
- (p. 146) “Borax and Nitre. The effects of nitre on borax are unknown; one only knows that nitre does not detonate.”
- (p. 238) “Arsenic regule with distilled vinegar. I did not perform experiments to find out the action of distilled vinegar upon arsenic; but it is to be presumed that it would act no better than distilled water.”
- (p. 255) “Arsenic and borax. The effect of these two substances one upon the other is unknown.
- (p. 304) “Nickel with nitre. The effects of pure nickel with nitre remain unknown.”
- volume 3, p. 176 “Platinum and nickel. We have not examined the properties of these two substances one on the other.”
I can do no better to close this section with a quotation, from G.B. de Saint-Romain. It expresses very articulately the powerful metaphor of a chemical compound being analogous to a word: Atoms in a compound are, according to Saint-Romain, just like letters and syllables in a word:
There is a difference between the characteristics of simple elements, which are atoms, and the characteristics of substances that are composed. The first are immutable and incorruptible like atoms, and the second are changing and transient like compounds. (…) Thus, atoms being immutable by their stability, their characteristics have the same immutability, but substances that are composed of several distinct parts are liable to change as their parts change location, or separate entirely.
(…)
The letters that compose syllables and words provide a very appropriate example for explaining this doctrine. Letters are immutable and by changing location they change the syllable or the word, without any change occurring in the appearance and in the substance or essence of the letters, which always remain the same in whichever condition and in whichever arrangement they are put. Now it is certain that letters, of which there are twenty-four, provide what is necessary for the formation of all syllables, all words, all dictions and all speeches, and even all books that are composed in the world. And as words and dictions, and syllables and speeches and even books change without the letters undergoing any change, similarly large and small compounds change and corrupt, without the atoms changing and perishing in any way.
(…)
Letters are the true portrait of atoms with regard to the composition or decomposition of things. As the substance, essence and nature of words depend on syllables, those of syllables depend on letters and their arrangement. Similarly the substance, essence and nature of substances depend on smaller ones, that are called corpuscles, and those of corpuscles depend on atoms and their arrangement.
Let me sum up this section:
That chemistry is a combinatorial art was set, or recognized very soon after it parted ways with alchemy. Some of the XVIIth and XVIIIth century chemists were very lucid on this score.