_{Click for Homage to Couper (11MB)}

A.S. Couper (age 27) in 1858 when he published this amazing paper, which would be his last.

Couper was deeply disturbed that delay on the part of his supervisor, AdolpheWurtz (perhaps because of the tone of the paper), allowed Kekulé to win priority for proposing tetravalence of carbon. When he lost his temper with Wurtz, he was expelled from the Paris laboratory. He returned to a chemistry assistantship in Edinburgh but suffered a mental breakdown within a few months. The next year his father died, and he himself, while recuperating, suffered sunstroke fishing. He was reinstitutionalized and never worked again. After his discharge three years later, he spent his last 30 years at home in a town near Glasgow, nursed by his mother, who was 90 when he died at 60.

If he had been able to keep his temper in dealing with Wurtz, he surely would have led a less tragic, more productive life, and organic chemistry may have developed differently.

[The following extracts show Couper's remarkable instinct for what turned out to be really important in organic chemistry. Note the density of remarkable ideas; every page has something great. The beginning suggests that the paper could have been entitled "The Emperor Has No Clothes". Right though he was, he did not become popular, or even famous.
The italic headings and the comments in square brackets are mine, not Couper's]

p. 104 - The opening sentence of Couper's paper is already remarkable. Few chemists of his, or any, time would have made so sweeping a claim for the primacy of theory in chemistry, which is often viewed as a fairly practical science whose end or goal should be to deliver "better things for better living". (Thanks to J. D. Dunitz, ETH Zurich, for pointing this out to me.) Perhaps this reflects Couper's long training in philosophy. He had taken his first course in chemistry only three years earlier.

THE end of chemistry is its theory. The guide in chemical research is a theory. It is therefore of the greatest importance to ascertain whether the theories at present adopted by chemists are adequate to explanation of chemical phaenomena, or are, at least, based upon the true principles which ought to regulate scientific research.

Should the principle which is therein adopted be applied to the common events of life, it will be found that it is simply absurd. Suppose that some one were to systematize the formation of letters into words that formed the contents of a book Were he to begin by saying that he had discovered a certain word which would serve as a type, and from which by substitution and double decomposition all the others are to be derived, - that he by this means not only could form new words, but new books, and books almost an infinitum, - he would state certainly an empirical truth. At the same time, however, his method would, judged by the light of common sense, be an absurdity. But a principle which common sense brands with absurdity, is philosophically false and a scientific blunder.

"Common sense" was a theme for the 18^th and 19^th Century philosophers of Couper's native Scotland.

It is impossible here to enter upon any extensive criticism of this theory. I can only remark that it is not merely an unprofitable figure of language, but is injurious to science, inasmuch as it tends to arrest scientific inquiry by adopting the notion that these quasi elements contain some unknown and ultimate power which it is impossible to explain. It stifles inquiry at the very point where an explanation is demanded, by putting the seal of elements, of ultimate powers, on bodies which are known to be anything but this.

Science demands the strict adherence to a principle in direct contradiction to this view. That first principle, without which research cannot advance a step, dare not be ignored; namely, that a whole is simple a derivative of its parts. As a consequence of this, it follows that it is absolutely necessary to scientific unity and research to consider these bodies as entirely derivative, and as containing no secret ultimate power whatever, and that the properties which these so-called quasi elements possess are a direct consequence of the properties of the individual elements of which they are made up.

It is necessary therefore in chemical research, in order to ascertain the various qualities and functions of the different elements, -

1. To consider the whole of chemistry as one.

2. To take into consideration every known combinate, and to study the character, functions, and properties displayed by each element for itself, in each of these combinated in all their different conditions and aspects. It is by a comparison of the different bodies among themselves that we are able to trace the part that is performed by each element separately.

3. To trace the general principles common to all the elements, noting the special properties of each.

This method is essentially different from that where one class of bodies [the type] is chosen as a point for the restriction of our views of the properties of the others - where only the qualities found in the first are to be measured out to the rest.

In applying this method, I propose at present to consider the single element carbon. This body is found to have two highly distinguishing characteristics: -

1. It combines with equal numbers of hydrogen, chlorine, oxygen, sulfur, &c.

2. It enters into chemical union with itself.

These two properties, in my opinion, explain all that is characteristic of organic chemistry.

[that CH₄ gives CCl₄ + 4 HCl shows that C, not H₄, is the central linking unit of the methane molecule (here we use modern atomic weights and subscripts)]

p. 111 - First Structural Formulae (for Methanol and Ethanol)

[Not so different from modern formulas. He uses rows of dots to indicate valence attachment, carbon and oxygen are doubled, and a single row of dots denotes the three attachments between C and H₃. The French version of his paper used solid lines, as we do.]

There is no reaction found where it is known that C₂ is divided into two parts. It is only consequent therefore to write, with Gerhardt, C₂ simply as C, it being then understood that the equivalent of carbon is (12) twelve.

_{Note that the French version of the paper used lines, instead of dots, to show bonds and showed the C-C bonds explicitly.}