He spent his evenings often in society, but wrote to a friend concerning himself: "Be not alarmed, my dear friend, as to the effect of worldly society on my mind.... There are in the intellectual being of all men paramount elements,—certain habits and passions that cannot change. I am a lover of nature with an ungratified imagination. I shall continue to search for untasted charms, for hidden beauties. My real, my waking existence is amongst the objects of scientific research. Common amusements and enjoyments are necessary to me only as dreams to interrupt the flow of thoughts too nearly analogous to enlighten and vivify."
During his vacations he explored most parts of Great Britain, the Hebrides, and Ireland, studying the geological structure, collecting agricultural knowledge, and making sketches. He never hesitated to ask questions, and often the miners and farmers thought they had never seen a person so inquisitive.
In his early years at the Institution he was asked to investigate astringent vegetables in connection with tanning. He entered the work with his usual ardor; visited tan-yards, and made the acquaintance of practical farmers. In 1802 he began to deliver, at the request of the Board of Agriculture, a course of lectures, "On the Connection of Chemistry with Vegetable Physiology." He had made himself acquainted with the different kinds of soil and the various methods of agriculture. For ten years he delivered these lectures at the meetings of the Board. They were published in book form, and translated into almost every European language.
"We feel grateful," said the Edinburgh Review, "for his having thus suspended for a time the labors of original investigation, in order to apply the principles and discoveries of his favorite science to the illustration and improvement of an art which, above all others, ministers to the wants and comforts of man."
He now continued his work with the voltaic pile or battery. If water could be decomposed by it, why not some substances heretofore regarded as simple or elementary bodies?
In October, 1806, he discovered that potash and soda can be decomposed, with potassium and sodium as resultant bases.
When he saw the minute globules of potassium burst through the crust of potash, and take fire as they entered the atmosphere, he is said to have bounded about the room in ecstatic delight, some time elapsing before he could compose himself sufficiently to go on with his experiment.
He had worked so constantly that he became very ill, and for several weeks his life was despaired of. All London was agitated over the expected death of the young chemist. Bulletins were prepared by the physicians morning, noon, and night, for the scores who came to ask concerning him.
When he had recovered and returned to his work, the Royal Institution provided him with a voltaic battery of six hundred double plates of four inches square, four times as powerful as any that had been constructed, and not long after, one of two thousand plates. Scientific papers were constantly coming from his pen. He soon decomposed boracic acid with the battery. By heating boron in oxygen, it burnt, and was reconverted into boracic acid. In his experiments with muriatic acid gas he found chlorine to be a simple substance, and discovered euchlorine, a compound of chlorine and oxygen.
He had already been made a fellow of the Royal Society at twenty-five, and at twenty-nine one of the secretaries. His lectures were crowded, as ever, by a thousand people. The Dublin Society now invited him to give courses of lectures in 1810 and 1811, which he did, ticket-holders each paying ten dollars for a course. So difficult was it to gain admission to the lectures that many offered from fifty to a hundred dollars for a course ticket!