to the Eoyal Society till January, 1784; and this delay, resulting from his desire to investigate the nature of the acid (nitric) formed on the passage of the electric spark through a mixture of hydrogen and oxygen, containing, as was afterwards found, a little nitrogen, caused his claim to the discovery of the composition of water to be contested by no less rivals than the celebrated James Watt and the great French chemist, Lavoisier. The modest, retiring and almost inordinately cautious man, whose personal history has just been detailed, has been accused of both incapacity and dishonesty, by men distinguished in letters and science, whose connection with the vexed question gives it an interest apart from its intrinsic merit.
Though Cuvier, in 1812, as secretary of the French Academy in reading an éloge on Cavendish could say that "his demeanor and the modest tone of his writings procured him the uncommon distinction of never having his repose disturbed either by jealousy or by criticism," Cuvier's distinguished, successor, Arago, in writing the éloge on Watt in 1839, charged that Cavendish learned the composition of water, not by experiments of his own, but by obtaining sight of a letter from Watt to Priestley. The French Academy heard the one side argued, and the British Association in the same year heard Cavendish's vindication delivered by the Rev. W. Vernon Harcourt, the president for that year.
At the very threshold of the water controversy we encounter a perplexing dilemma. Two unusually modest and unambitious men, universally respected for their integrity, famous for their discoveries and inventions, and possessed of rare intelligence, are suddenly found standing in a hostile relation to each other, and, although declining to publish their own unquestioned achievements, are seen contending for a single discovery, which the one believes the other to have learned at second hand from the revelations made to a common friend, and which that other accuses his rival of having gathered from a letter that he was allowed to peruse. A misunderstanding such as this would never have occurred had Watt and Cavendish been intimate in 1783. As yet, however, the friendly intercourse which afterwards subsisted between them had not commenced. The one was resident in London, the other in Birmingham, and each was informed of the other's doings by third parties, upon whom mainly though not equally, rests the blame of having occasioned the water controversy. Those in question are: Dr. Priestley, J. A. DeLuc and Sir Charles Blagden, all eminent men of unblemished character. Through the first, knowledge of Cavendish's experiments passed to Watt, and a knowledge of Watt's conclusions to Cavendish; by the second. Watt was informed that Cavendish had deliberately pilfered his theory; and the third, who was Cavendish's assistant, reported the latter's conclusions as well as those of Watt, to Lavoisier, whom he accused of appropriating the ideas of both English
