A small bubble of air remained unabsorbed... if there is any part of the phlogisticated air [nitrogen] of our atmosphere which differs from the rest, and cannot be reduced to nitrous acid, we may safely conclude that it is not more than 1/120 part of the whole.
Cavendish did not realize the significance of the remaining small bubble. Not until a century later were the air’s Noble Gases appreciated.

His [Henry Cavendish's] Theory of the Universe seems to have been, that it consisted solely of a multitude of objects which could be weighed, numbered, and measured; and the vocation to which he considered himself called was, to weigh, number and measure as many of those objects as his allotted three-score years and ten would permit. This conviction biased all his doings, alike his great scientific enterprises, and the petty details of his daily life.

Cavendish was a great Man with extraordinary singularities—His voice was squeaking his manner nervous He was afraid of strangers & seemed when embarrassed to articulate with difficulty—He wore the costume of our grandfathers. Was enormously rich but made no use of his wealth... He Cavendish lived latterly the life of a solitary, came to the Club dinner & to the Royal Society: but received nobody at his home. He was acute sagacious & profound & I think the most accomplished British Philosopher of his time.

Only about seventy years ago was chemistry, like a grain of seed from a ripe fruit, separated from the other physical sciences. With Black, Cavendish and Priestley, its new era began. Medicine, pharmacy, and the useful arts, had prepared the soil upon which this seed was to germinate and to flourish.