He found that the platina wire at the positive pole rapidly corroded, and became covered with a chocolate powder, and what appeared by its inflammability to be hydrogen separated at the negative pole. He tried a number of other experiments with different vessels and various electrodes, but with no better success.
He suffered great inconvenience from the fumes of hydrofluoric acid; they acted vigorously on the nails, and produced a most painful sensation when in contact with the eyes. The conclusion he drew from his experiments was that fluoric acid is “composed of hydrogen, and a substance as yet unknown in a separate form, possessed like oxygen and chlorine, of the negative electrical energy, and hence determined to the positive surface, and strongly attracted by metallic substances.”
He then attempted to isolate the fluoric principle by treating various fluates in a platinum apparatus with chlorine gas, but although there was evidence of decomposition and the platinum was violently acted upon, he could obtain no new gaseous matter.
“From the general tenour of the results that I have stated, it appears reasonable to conclude that there exists in the fluoric compounds a peculiar substance, possessed of strong attractions for metallic bodies and hydrogen, and which combined with certain inflammable bodies forms peculiar acids, and which in consequence of its strong affinities and high decomposing agencies, it will be very difficult to examine in a pure form, and for the sake of avoiding circumlocution, it may be denominated fluorine, a name suggested to me by M. Ampère.
“It is easy to perceive in following the above theory, that all the ideas current in chemical authors respecting the fluoric combinations, must be changed. Fluor-spar, and other analogous substances, for instance, must be regarded as binary compounds of metals and fluorine.”
Davy’s views are now part of current chemical doctrine, and his previsions as to the nature of fluorine and its extraordinary chemical activity have been verified in the most striking manner by the admirable investigations of Moissan.
CHAPTER IX.
DAVY AND FARADAY—IODINE.
The year 1813 is memorable in the history of the Royal Institution, from the fact that Faraday’s long and honourable association with it dates from that time. The circumstances which led to this connection were subsequently stated by himself in the following letter to Dr. Paris:—
“Royal Institution, Dec. 23rd, 1829.
“My dear Sir,—You ask me to give you an account of my first introduction to Sir H. Davy, which I am very happy to do, as I think the circumstances will bear testimony to his goodness of heart.
“When I was a bookseller’s apprentice, I was very fond of experiment and very averse to trade. It happened that a gentleman, a member of the Royal Institution, took me to hear some of Sir H. Davy’s last lectures in Albemarle Street. I took notes, and afterwards wrote them out more fairly in a quarto volume.
“My desire to escape from trade, which I thought vicious and selfish, and to enter into the service of Science which I imagined made its pursuers amiable and liberal, induced me at last to take the bold and simple step of writing to Sir H. Davy, expressing my wishes, and a hope that, if an opportunity came in his way, he would favour my views; at the same time I sent the notes I had taken at his lectures.
“The answer, which makes all the point of my communication, I send you in the original, requesting you to take great care of it, and to let me have it back, for you may imagine how much I value.
“You will observe that this took place at the end of the year 1812, and early in 1813 he requested to see me, and told me of the situation of assistant in the laboratory of the Royal Institution, then just vacant.
“At the same time that he thus gratified my desires as to scientific employment, he still advised me not to give up the prospects I had before me, telling me that Science was a harsh mistress; and, in a pecuniary point of view, but poorly rewarding those who devoted themselves to her service. He smiled at my notion of the superior moral feelings of philosophic men, and said he would leave me to the experience of a few years to set me right on that matter.
“Finally, through his good efforts I went to the Royal Institution early in March of 1813, as assistant in the laboratory; and in October of the same year went with him abroad as his assistant in experiments and in writing. I returned with him in April 1815, resumed my station in the Royal Institution, and have, as you know, ever since remained there.
“I am, dear Sir, very truly yours
“M. Faraday.”
The answer which Faraday characteristically says makes all the point of the foregoing communication is as follows:—