A HISTORY OF SCIENCE 



When a young man, as a pupil of Dr. Black, he had 

 become imbued with the enthusiasm of his teacher, 

 continuing Black's investigations as to the properties 

 of carbonic-acid gas when free and in combination. 

 One of his first investigations was reported in 1766, 

 when he communicated to the Royal Society his ex- 

 periments for ascertaining the properties of carbonic- 

 acid and hydrogen gas, in which he first showed the 

 possibility of weighing permanently elastic fluids, al- 

 though Torricelli had before this shown the relative 

 weights of a column of air and a column of mercury. 

 Other important experiments were continued by Caven- 

 dish, and in 1784 he announced his discovery of the 

 composition of water, thus robbing it of its time-hon- 

 ored position as an "element." But his claim to pri- 

 ority in this discovery was at once disputed by his 

 fellow-countryman James Watt and by the French- 

 man Lavoisier. Lavoisier's claim was soon disallowed 

 even by his own countrymen, but for many years a 

 bitter controversy was carried on by the partisans of 

 Watt and Cavendish. The two principals, however, 

 seem never to have entered into this controversy 

 with anything like the same ardor as some of their suc- 

 cessors, as they remained on the best of terms. 1 It is 

 certain, at any rate, that Cavendish announced his dis- 

 covery officially before Watt claimed that the an- 

 nouncement had been previously made by him, "and, 

 whether right or wrong, the honor of scientific discov- 

 eries seems to be accorded naturally to the man who 

 first publishes a demonstration of his discovery." 

 Englishmen very generally admit the justness of Cav- 

 endish's claim, although the French scientist Arago, 



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