One explanation of this untoward haste is to be found in the position in which Davy was placed. He simply hungered for scientific fame, and his appetite grew by what it fed on. There was at the time the most intense spirit of rivalry between the English and French chemists—it was a phase of the national feeling which actuated the two peoples—and, in spite of his phrases, Davy keenly felt what he considered an intrusion into his own field of work. His illness had thrown him back, and the French chemists had stolen a march on him in the meantime. Moreover, he had Berzelius on his flank. All these circumstances, whilst they impelled him to activity, were unfavourable in a man of Davy’s temperament to the incubatory period, “the wambling in the wame” process, which is often needed before the true aspect and meaning of things are perceived; and there is no doubt that the fear of being anticipated urged him to the expression of hypotheses and surmises which at a later and calmer period he regretted and renounced.
But such was his position in England at this period, that a Bakerian lecture seemed to be expected from him at each succeeding session of the Royal Society as a matter of course, and he was always ready to respond to the expectation, even if he did not invariably satisfy it.
On November 16th, 1809, he read his fourth Bakerian lecture. It was “On some new Electrochemical Researches on various Objects, particularly the metallic Bodies, from the Alkalies and Earths, and on some Combinations of Hydrogene.” He begins by again drawing attention to the various surmises which had been made respecting the true nature of potassium and sodium. Although these substances had been isolated, and in the hands of chemists for upwards of two years, their properties were so extraordinary when compared with those of the metals in general, that many philosophers hesitated to consider them as true metals. Gay Lussac and Thenard, as already mentioned, regarded them as compounds of potash or soda with hydrogen; Curaudau as combinations of carbon or carbon and hydrogen with the alkalis; whilst an ingenious inquirer in this country communicated to Nicholson’s Journal his belief that they were really composed of oxygen and hydrogen! Davy, in the light of the fuller knowledge he obtained from Gay Lussac and Thenard’s paper in the “Mem. d’Arcueil”—a copy of which he owed to Berthollet—had no difficulty in again proving “that by the operation of potassium upon ammonia, it is not a metallic body that is decompounded, but the volatile alkali, and that the hydrogen produced does not arise from the potassium, as is asserted by the French chemists, but from the ammonia.”
M. Curaudau’s hypothesis is shown to be based upon the accidental association of naphtha with the metals he employed. In repeating some experiments of Ritter’s, designed to show that potassium contained hydrogen, Davy was led to the discovery of telluretted hydrogen, the properties of which he describes in some detail. Tellurium at that time was regarded as a metal, but Davy points out its strong analogies to sulphur, with which element, indeed, it is now classed. Incidentally he throws light upon the nature of the intolerably fetid product known as “the fuming liquor of Cadet,” obtained by distilling acetate of potash with arsenious oxide. On account of its extreme inflammability, it was thought by Davy that this liquid might possibly be a pyrophorus or volatile alloy of potassium and arsenic.
“From a repetition of the process I find that though potash is decompounded in this operation yet that the volatile substance is not an alloy of potassium but contains charcoal and arsenic probably with hydrogen. The gases not absorbable by water given off in this operation are peculiar. Their smell is intensely fetid. They are inflammable, and seem to contain charcoal, arsenic and hydrogen: whether they are mixtures of various gases, or a single compound, I am not at present able to decide.”
So far as it goes, this description of the nature of the substance is correct; it was Bunsen, in 1837, who first demonstrated the real character of “the fuming liquor of Cadet.”
The paper is noteworthy for the clear distinction which is drawn for the first time between potash hydrate (potassium hydroxide of modern nomenclature) and potassium oxide, the product formed by heating the metal in ordinary oxygen.
There is much in the rest of the paper that is ingenious and suggestive, and not a few isolated facts that seem to have been lost sight of, or rediscovered by subsequent observers, such, for example, as the action of potassium upon metallic iron—an action which has vitiated the attempts to determine the vapour density of that metal in iron vessels. It is curious to note with what persistency Davy clings to the belief that nitrogen will turn out to be a compound substance, and with what pertinacity he importunes it to give up its components. At times he thinks he is on the verge of proof. “I hope on Thursday,” he wrote to his friend Children, “to show you nitrogen as a complete wreck, torn to pieces in different ways.” But still nitrogen, with that passive immutability which is characteristic of it, in spite of every form of torture, remained whole and indissoluble. On this point he wrote in the Laboratory Journal under date February 15th:—“Were a description, indeed, to be given of all the experiments I have made, of all the difficulties I have encountered, of the doubts that have occurred, and the hypotheses formed——.” But the sentence was not finished. The attack was renewed and continued throughout the whole of the spring and summer, until, fairly baffled, Davy confessed himself beaten, and turned his attention to other matters. The condition of his laboratory at this time may be gleaned from the following note in the Journal:—
“Objects much wanted in the laboratory of the Royal Institution: cleanliness, neatness and regularity.
“The laboratory must be cleaned every morning when operations are going on before ten o’clock.
“It is the business of W. Payne to do this, and it is the duty of Mr. E. Davy to see that it is done and to take care of and keep in order the apparatus.
“There must be in the laboratory pen, ink, paper, and wafers, and these must not be kept in the slovenly manner in which they are usually kept. I am now writing with a pen and ink such as was never used in any other place.”
Then follows a list of articles wanting, “including most of the common metallic and saline solutions.”