Guided by the _Elements_ of Lavoisier, encouraged by the friendship of Gregory Watt (a son of James Watt) and by another gentleman of university education, stimulated by contact with the Cornish mining industry, Davy pursued this new study with zeal, and within a few months had written two essays full of daring generalizations on the physical sciences. These were published early in 1799. Partly on the basis of the ingenious experiment mentioned in the preceding chapter, he came to the conclusion that "Heat, or that power which prevents the actual contact of the corpuscles of bodies, and which is the cause of our peculiar sensations of heat and cold, may be defined as a peculiar motion, probably a vibration, of the corpuscles of bodies, tending to separate them." Other passages might be quoted from these essays to show how the gifted youth of nineteen anticipated the science of subsequent decades, but in the main these early efforts were characterized by the faults of overwrought speculation and incomplete verification. He soon regretted the premature publication of his studies. "When I consider," he wrote, "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." In the mean time Davy had been chosen superintendent of the Pneumatic Institution at Bristol by Dr. Beddoes, its founder. It was supported by the contributions of Thomas Wedgwood and other distinguished persons, and aimed at discovering by means of experiment the physiological effect of inhaling different gases, or "factitious airs," as they were called. The founding of such an establishment has been termed a scientific aberration, but the use now made in medical practice of oxygen, nitrous oxide, chloroform, and other inhalations bears witness to the sanity of the sort of research there set on foot. Even before going to Bristol, Davy had inhaled small quantities of nitrous oxide mixed with air, in spite of the fact that this gas had been held by a medical man to be the "principle of contagion." He now carried on a series of tests, and finally undertook an extended experiment with the assistance of a doctor. In an air-tight or box-chamber he inhaled great quantities of the supposedly dangerous gas. After he had been in the box an hour and a quarter, he respired twenty quarts of pure nitrous oxide. He described the experience in the following words:--