On the Substitution Law and the Theory of Types (letter to Justus Liebig)
Paris, 1 March 1840
I am eager to communicate to you one of the most striking facts of organic chemistry. I have confirmed the substitution theory in an extremely remarkable and completely unexpected manner. Only now can one appreciate the great value of this theory and foresee the immense discoveries that it promises to reveal. The discovery of chloroacetic acid and the constancy of types in chlorinated compounds derived from ether and ethyl chloride has led me to experiments which I shall now describe. I passed a stream of chlorine through a solution of manganese acetate [MnO + C4H6O3] under the influence of direct sunlight. After 24 hours I found in the liquid superb crystals of a violettish-yellow salt. The solution contained only this salt and hydrochloric acid. I have analyzed this salt: it was manganese oxide chloroacetate. Thus far nothing out of the ordinary, a simple substitution of hydrogen in acetic acid by an equal number of equivalents of chlorine, already knows form the beautiful work on chloroacetic acid. When this salt was heated to 110° in a stream of dry chlorine, it was converted with evolution of oxygen gas into a new golden-yellow compound which analyzed for the formula MnCl2 + C4Cl6O3. There was thus substitution of oxygen in the base by chlorine, which has been observed in numerous circumstances. Upon warming, the new substance dissolves in very pure chloral, and I used this solvent, which is stable to chlorine, to continue treatment with this reagent. For four days I passed dry chlorine through the liquid, held always near its boiling point. During this time a white substance continually precipitated, which careful examination proved to be manganese oxide. Some time after the precipitation ceased, I cooled the liquid and obtained a third substance as tiny, greenish-yellow, silky needles. This was C4Cl10O3, or in other terms, it was manganese acetate in which all hydrogen and the manganese oxide had been replaced by chlorine. Its formula should be written Cl2Cl2 + C4Cl6O3. There were thus 6 atoms of chlorine in the acid, the other four atoms representing manganese oxide. Since hydrogen, manganese, and oxygen may be replaced by chlorine, there is nothing surprising in this substitution.
But this was not the end of this remarkable series of substitutions. By reacting chloride again with the solution of this material in water, there was evolution of carbonic acid, and on cooling to +2° the liquid deposited a yellowish mass of small plates, extremely similar to chlorine hydrate. Thus it contained only chlorine and water. But on measuring the vapor density I found that it was formed of 24 atoms of chlorine and one of water. Thus there was complete substitution of all the elements of manganese acetate. The formula of the substance should be expressed as Cl2Cl2 + Cl8Cl6Cl6 + aq. For all I know, in the decolorizing action of chlorine, hydrogen is replaced by chlorine, and the cloth, which is now being bleached in England, preserves its type according to the substitution laws.* I believe, however, that atom-for-atom substitution of carbon by chlorine is my own discovery. I hope you will take note of this in your journal and be assured of my sincerest regards, etc.
* I have just learned that there is already in the London shops a cloth of chlorine thread, which is very much sought after and preferred above all others for night caps, underwear, etc.
Wöhler had written this spoof of Dumas and the Type or Substitution Theory for fun, sending copies to Berzelius and Liebig, his colleagues in developing the Radical Theory. Wöhler was aghast when he discovered that Liebig had decided to publish it in the journal that he had founded in 1832 and was becoming the principal German-language organ of the developing field of organic chemistry. Presumably Dumas was not amused, which didn't bother Liebig in the least. The following extracts from letters reveal something about the personalities of these humans.
Göttingen 10. Febr. 1840
... The chemical machinations and prattle of the Frenchman, the never-ending song about substitutions, is completely nauseating. So much of their data is lies, pure guesswork, pure speculation, and yet presented as fact.
But enough of the stupid stuff. My paper is about to run out.
Stockholm d. 10. März 1840
Many thanks, best friend, for both of your letters and for exchanging the 50 gold Friedrichs, which has really been convenient for me, and even more I thank you for your parody of Dumas's way of announcing discoveries. It is so masterful, that it really deserves to be read generally. It makes me laugh even harder than the one about fermentation theory.
A few days ago I received a letter from Dumas with thanks for the certificate as Fellow of the (Swedish) Academy, which he received a short time ago. In fact I had to first remind him through an acquaintance that when one receives such a certificate, one must either return it, if it is unwelcome, or thank someone for it. His letter was as crawling as his tongue. To convey his reverence to the Academy, he had wanted to submit a paper on the present state, upon which he and I are of different minds, how he was very apologetic, but commitments and sickness, from which he had recovered, had kept him from doing so, and now he could no longer hesitate to express his thanks to the Academy. Still on the day after the date of this letter he presented his opus to the Paris Academy, as I saw in the newspapers.
Göttingen 25ten April 1840
... That the piece about Substitution Theory didn't displease you, and that you remarked that it deserved more general circulation, has become a real problem for me, since Liebig, without my knowledge or permission, has actually had it published, although of course without my name, having altered a few points here and there and added a few new witticisms. Before I finished the letter which I had written you in sport, I decided, since I also enjoyed it, to send a copy to Liebig in the form of a latter dated from Paris, without the remotest idea that he could be so crazy as to publish it in the Annalen. It was signed S. Ch. Windler (Schwindler) -- This by way of explanation.
Stockholm d. 4. Mai 1840
... I can't wait to hear from you. Liebig has sent me a reprint of Windler's letter from Paris. It is masterful. Even though I already knew the contents, it was impossible not to laugh out loud.
I've just completed my Annual Review for 1840 and it is in press. I couln't omit giving Dumas's new Substitution Theory an honorable mention. I even stole a bit from Windler. In discussing his chemical types and mentioning his own examples, I added that he hadn't extended the Substitution Theory as far as he could have from his rules, i.e. to the exchange of carbon also, so that methyloxide gas would give another gas of the same type, namely Cl2ClCl3 from C4OH3. Is Dumas deranged? Or what must someone be missing to be able to write such miserable material seriously? What does Liebig say about all this? Has he cast his eyes over this theory? Our correspondence seems to be over again. [Liebig had a hard time getting along with people] I haven't had a letter from him since August, although I've written him twice without receiving a reply. Windler's letter came in an envelope with no more message than the address. If he himself were not convinced of the craziness of this theory, he would certainly not have put it in his journal. I hope he still wishes me well and considers me a friend.…
Your Friend, Berzelius