“When pure oxyd of lead is heated as much as possible, included from light, it remains unaltered; but when exposed to the light of a burning-glass, or even of a candle, phosoxygen is generated and the metal revivified.”
“Oxygenated muriatic acid [chlorine] is a compound of muriatic acid, oxygen and light, as will be hereafter proved. The combined light is not sufficient to attract the oxygen from the base [muriatic acid] to form phosoxygen; but its attraction for oxygen renders the [oxygenated muriatic] acid decomposable. If this acid be heated in a close vessel and light excluded no phosoxygen is formed; but if it be exposed to the solar light, phosoxygen is formed; the acid loses its oxygen and light and becomes muriatic acid.”
“A plant of Arenaria Tenuifolia planted in a pot filled with very dry earth, was inserted in carbonic acid, under mercury. The apparatus was exposed to the solar light, for four days successively, in the month of July. By this time the mercury had ascended considerably. The gas in the vessel was now measured. There was a deficiency of one-sixth of the whole quantity. After the carbonic acid was taken up by potash, the remaining quantity, equal to one-seventh of the whole, was phosoxygen almost pure. From this experiment, it is evident that carbonic acid is decomposed by two attractions; that of the vegetable for carbon and of light for oxygen: the carbon combines with the plant, and the light and oxygen combined are liberated in the form of phosoxygen.”
The accounts which Davy gives of his experiments, as well as of the phenomena which he professes to have observed, may awaken an uneasy doubt as to his absolute integrity; for, it is hardly necessary to point out, he could not possibly have obtained the results which he describes. The presence or absence of light in no wise affects the decomposition by heat of minium; chlorine, as he himself subsequently established, contains no oxygen; and a plant is incapable of decomposing pure undiluted carbonic acid, even in the brightest sunshine. But the work of a youth of nineteen, imaginative, sanguine, and impetuous, with no training as an experimentalist, and with only a limited access to scientific memoirs, cannot be judged by too severe a canon. The faculty of self-deception, even in the largest and most receptive minds, often in those of matured power and ripened experience, is boundless. Davy himself affords an exemplification of the truth of his own words, written years afterwards: “The human mind is always governed not by what it knows, but by what it believes; not by what it is capable of attaining, but by what it desires.”
It is not necessary to show how the presumptuous youth drove his hobby with all the reckless daring of a Phæton. Phlogiston and oxygen had in turn been the central conceptions of theories of chemistry; phosoxygen was to supplant them. It was to explain everything—the blue colour of the sky, the electric fluid, the Aurora Borealis, the phenomena of fiery meteors, the green of the leaf, the red of the rose, and the sable hue of the Ethiopian; perception, thought, and happiness; and why women are fairer than men. But Jupiter, in the shape of a Reviewer, soon hurled the adventurous boy from the giddy heights to which he had soared. The “West Country Collection” received scant sympathy from the critics, and the phosoxygen theory was either mercilessly ridiculed, or treated with contempt.
There is no doubt that Davy keenly felt the position in which he now stood. His pride was humbled, and the humiliation was as gall and wormwood. The vision of fame which his ardour had conjured up on the top of the Bristol coach—was it all a baseless fabric, and its train of honours and emoluments an insubstantial pageant? All he could plead was that his critics had not understood that these experiments were made when he had studied chemistry only four months, when he had never seen a single experiment executed, and when all his information was derived from Nicholson’s “Chemistry” and Lavoisier’s “Elements.” But his good sense quickly came to his rescue. After the first feelings of anger and mortification had passed, he recognised the justice of his punishment, much as he might resent the mode in which it was inflicted. How keen was the smart will appear from the following reflection, written in the August of the year in which the essays were published:—
“When I consider the variety of theories that may be formed on the slender foundation of one or two facts, I am convinced that it is the business of the true philosopher to avoid them altogether. It is more laborious to accumulate facts than to reason concerning them; but one good experiment is of more value than the ingenuity of a brain like Newton’s.”
About the same time he wrote:—
“I was perhaps wrong in publishing, with such haste, a new theory of chemistry. My mind was ardent and enthusiastic. I believed that I had discovered the truth. Since that time my knowledge of facts is increased—since that time I have become more sceptical.”
In the October of the same year he wrote:—
“Convinced as I am that chemical science is in its infancy, that an infinite variety of new facts must be accumulated before our powers of reasoning will be sufficiently extensive, I renounce my own particular theory as being a complete arrangement of facts: it appears to me now only as the most probable arrangement.”
By the end of the year the repentance was complete, and recantation followed. In a letter which appeared in Nicholson’s Journal in February, 1800, he corrects some of the errors into which he had fallen, and says, “I beg to be considered as a sceptic with regard to my own particular theory of the combinations of light, and theories of light in general.” To the end of his days Davy never forgot the lesson which his earliest effort had taught him; and there is no question that the memory of it acted as a salutary check on the exuberance of his fancy and the flight of his imagination. The wound to his self-love was, however, never wholly healed. Nothing annoyed him more than any reference to Beddoes’s book, and he declared to Dr. Hope that he would joyfully relinquish any little glory or reputation he might have acquired by his later researches were it possible to withdraw his share in that work and to remove the impression he feared it was likely to produce.