I
The Chemistry Student THE THEORY OF TYPES-A SATIRICAL SKETCH HAROLD B. FRIEDMAN, GEORGIA SCHOOL OF TECHNOLOGY, ATLANTA, GEORGIA
Satire has ever been one of the most powerful weapons of literary warfare, which fact Bulwer-Lytton no doubt had in mind when he caused Richelieu to say that "The pen is mightier than the sword." Before presenting the following bit of satire relating to chemistry, it is well to recall the incidents which led up to it. In the historical development of chemical theories one finds the period 1830-40 characterized by the bitter contention of adherents to rival theories of molecular structure. Berzelius and his dualistic ideas were slowly giving way to the formulation of the radical theories of Liebig and Wohler, and the 6 r s t theory of types by Dumas. The year 1828, i t may be recalled, marked the overthrow of the sharp boundary between organic and inorganic chemistry, as the result of Wohler's synthesis, from ammonium cyanate, of urea, formerly obtained only from vital processes. Other syntheses soon followed, all of which made unnecessary the existence of a "vital force." When the conservative Berzelius realized that the fundamental laws of combination of inorganic chemistry applied to organic compounds as well, be set out to explain the phenomena a t h w d with a dualistic electrochemical theory. Reluctant to remove oxygen from the important place that i t occupied in his older theories, he assumed that the "base" or "radical" with which i t was combined in inorganic compounds was simple, while in organic compounds a complex radical. In 1832, the concept of "radical" took on a more serious significance with the publication by Liebig and Wohler of their classical work, "Researches on the Radical of Benzoic Acid."' In these researches they showed the persistence, throughout a series of reactions, of the group CmHlo02, which they called benzoyl. For example, benzaldehyde was CiaH1o02,Hz; benzoic acid, ClaHloOz~O.H~O; benzoyl chloride, ClaHloOzClz, and so on. - He found Shortly after this, Dumas made a remarkable disco~ery.~
' Annalen der Chemie, 3, 249 (1832). One evening, a t a soirde a t the Tuileries, during the reign of Charles X, the pleasure of the entertainment was seriously marred by the fact that the wax candles emitted very unpleasant, irritating fumes, and were remarkable far the smokiness of their flames. The investigation of the cause of their peculiar behavior was entrusted t o Dumas. The irritating fumes were found t o he hydrochloric acid, and Dumas had no difficulty in discovering that they were due to the candles having been made from wax which had been bleached by chlorine. He soon found that, when chlorine acts on compounds
633
634
JOURNAL OF CHEMICAL EDUCATION
MARCH, 1930
that in such a compound as CH4, the hydrogens might be successively replaced by other elements, such as chlorine, quite different from hydrogen, yet a t each stage of the substitution producing a compound not markedly different from the preceding one. This phenomenon he found to be very widespread and general, and to account for i t he devised his Theory of Types. In this he likened the elements of a compound to a solar system, a sun with its accompanying planets, the units of which were held together by the forces of mutual attraction. If a unit of such a system be replaced by another, even of a different nature, the result would be not unlike the original, just as if a planet of our solar system were substituted by another, the properties of the mechanical system would remain approximately the same as before. In other words, the properties of a molecule depended more upon the number and relative positions of its component atoms than upon their nature. Instances of substitution increased rapidly, and the theory became very popular. Dumas, however, in his enthusiasm for it, applied the theory to every imaginable reaction, even seeing substitution in many cases where the analogy was very far-fetched. He admitted suhstitution, not only of hydrogen, but also of oxygen, and even of carbon, by elements or groups. His efforts a t application went to such extremes that they soon brought forth the ridicule of the more thoughtful and conservative-minded, who, willing to admit the truth of the basic idea, would not go to the limits Dumas would take them in making his theory general. It is one of these attempts a t ridicule tlyt is presented here, as a very interesting oddity which appeared in a journal of the time.3 It is a letter, written by one S. C. H. Windler, to Liebig, editor of the Annalen, begging him to announce in his journal "one of the most brilliant facts of organic chemistry.'' He proceeds to outline the details of a spurious piece of research, in which starting with manganese acetate, by passing in chlorine, he successively replaces the hydrogen, the oxygen, the carbon, and finally even the manganese, ending up with a compound of pure chlorine, but preserving the original type! The s(ch)windler was Wohler-and there is a footnote, added presumably by Liebig himself in which he says that some of this new substance, of nothing but chlorine, has been spun into cloth and is already quite popular in the shops and hospitals of London, containing hydrogen, the hydrogen may he removed and replaced by an equivalent quantity of chlorine. This observation was not, it is true, a new one; Gay-Lussac. Paraday, and Liebig and Wahler had all observed that hydrochloric add is emitted, and chlorine fixed by organic bodies. But Dumas &st systematically examined this kind of action, laid down the rules which it follows, and, jointly with Laurent, who first perceived their significance, developed their consequences-"Justus von Liebig, His Life and Work," by Shenstane (Macmillan). a Annalen der Chemie, 33, 308 (1840).
VOL.7, No. 3
035
THE CHEMISTRY STUDENT
and is preferred to all others for nightcaps, drawers, etc.! The letter, although in the German journal, is in French, and its translation follows. On the Substitution Law and the Theory of Types Written Communication to J. I,. Paris, March 1, 1840 Sir:
I hasten to communicate to you one of the most striking facts of organic chemistry. I have verified the theory of substitution in an extremely remarkable and perfectly unexpected rnsnner. I t is only from the present that one will he able to appreciotc the high \.due of this ingcnims thwrs. and tint unr will be able to fur^,^^ the imrnmsr disco\wi:s that it promises to realize for us. The discovery of chloracetic acid and the constancy of the types in compounds containing chlorine, derivatives of ether and ethyl chloride, have led me to experiences which I a m now going to describe. I passed aJtream of chlorine through a solution of manganese acetate, under the direct influence of sunlight. After 24 hours I found in the liquid a superb crystallization of a violet-yellow colored salt. The solution contained only the salt itself and some hydrochloric add. I analyzed the salt: i t was manganous chloracetate. Thus far nothing extraordinary, simple substitution of the hydrogen of the acetic acid by a like number of equivalents of chlorine, already known through the beautiful researches on chloracetic acid. This salt when heated at 110' in a stream of dry chlorine was converted with liheration of oxygen gas into a new eolden vellow comnound. whose aualvsis led for its comuosition to the formula MnCln C,ClsOs. There was then, suhstitntion of the oxygen of the base by chlorine, what one has observed in a great number of cases. The new suhstance was dissolved in very pure chloral with the aid of heat, and I used this liquid, stable with chlorine, to continue the treatment with this went. I passed dry chlorine into it for 4 days, keeping the liquid always very near its boiling point. during this time there was constantly deposited a white suhstance, which in a careful examinatipn was recognized as manganous chloride. I cooled the liquid some time after, when there was no more of the precipitate and obtained a third substance in small greenish-yellow silky needles. This was or in other words was the acetate of manganese in which all of the hydrogen C,C~,OO~, and the oxide of manganese had been replaced by chlorine. Its formula ought to he written ClnCh 6CI6Os. There were therefore 6 atoms of chlorine in the acid, the four other atoms represented the oxide of manganese. As hydrogen, manganese, and oxygen can be replaced by chlorine, one will see nothing surprising in this substitution. But this was not yet the end of this remarkable series of snhstitutions. I n causing chlorine to act anew on a solution of this substance in water, there was a liberation of carbonic add, and on cooling the liquid to + Z O there was deposited a yellowish mass formed of little leaflets. closely resembling the hydrate of chlorine. Also i t contained only chlorine and water. But in taking the density of its vapor I found that it was formed of 24 atoms of chlorine and one part of water. Behold then the most perfect substitution of all the elements of manganese acetate. The formula of the substance ClsClsCls aq. Although I know that in the decolorwould be exuressed hv CllCll king action of chlorine there is a repIacement of hydrogen by chlorine and that the cloths which are now bleached in England preserve their types according to the laws of substitution, I believe nevertheless that the substitution of carbon by chlorine, atom for atom, is a discovery which belongs to me.-Be willing to take note in your journal and accept, etc. S. C. H. Windler
+
+
+
+
~
The footnote is as follows:
636
JOURNAL OF CHEMICAL EDUCATION
.
MARC%,1930
I have just learned that there are already in the shops in London fabrics of spun chlorine, quite sought after in hospitals and preferred to all others for night caps, drawers, etc.
Nevertheless, in spite of these efforts a t ridicule, i t was realized that there was something fundamentally reliable in the conceptions of the Theory of Types. And while its opponents never accepted it bodily, they adopted the idea and merged it with the radical theory of their own, from which i t was possible for Gerhardt to develop a second Type Theory. With this he was able to coijrdinate all the phenomena known at that time, to discover many new compounds, and in some cases to predict their properties.
