"'I shall now give you my last command,' Cavendish went on to say, 'I am going to die. I shall, upon your departure, lock my room. Here let me be alone for eight hours. Tell no one. Let no person come near. When the time has passed, come and see if I am dead. If so, let Lord George Cavendish know. This is my last command. Now, go.'
"The servant knew from long experience that to dispute his master's will would be useless. He bowed, therefore, and turned to go away.
"'Stay—one word!' added Cavendish. 'Repeat exactly the order I have given.'
"Edgar repeated the order, promised obedience once more, and retired from the chamber."
The servant did not keep his promise, but called to his master's bedside Sir Everard Home, a distinguished physician.
"Sir Everard inquired if he felt ill.
"'I am not ill,' replied Cavendish; 'but I am about to die. Don't you think a man of eighty has lived long enough? Why am I disturbed? I had matters to arrange. Give me a glass of water.'
"The glass of water was handed to him; he drank it, turned on his back, closed his eyes, and died.
"This end of a great man, improbable as are some of the incidents narrated, is no fiction of imagination. Sir Everard Home's statement, read before the Royal Institution, corroborates every particular. The mental constitution of the philosopher, puzzling enough during his life, was shrouded certainly in even greater mystery in his death."
It is as a chemist that Cavendish stands preeminent. Without instructors, without companionship, in the solitary rooms of his dwelling, he meditated and experimented. The result of his researches he communicated in papers read to the Royal Society, and these are quite numerous. He was the first to demonstrate the nature of atmospheric air and also of water. He was the discoverer of nitrogen and several gaseous bodies. He did much to overthrow the phlogiston theory, which was universally accepted in his time; and his researches upon arsenic were of the highest importance. There is scarcely any department of chemistry which he did not enrich by his discoveries. He was a close student of electrical phenomena, and made many discoveries in this department of research. He was also an astronomer and observed the heavens with his telescopes with the deepest interest. Some of his most important discoveries were unknown until after his death, as they were hidden in papers, which, for some reason, he would not publish.