PRIESTLEY. 409 



trine of Necessity ;' * On the Roman Catholic Claims ;' 

 * On the French Revolution ;' ' On the American 

 War ;' beside twenty volumes of tracts in favour of 

 the Dissenters and their rights. His general works 

 fill twenty-five volumes,* of which only five or six are 

 on scientific subjects : his publications being in all one 

 hundred and forty-one (in one year ten), of which 

 only seventeen are on scientific matters. He is one of 

 the most voluminous writers of any age or country, 

 and probably he is of all voluminous writers the one 

 who has the fewest readers. This arises from the circum- 

 stance that, though his political opinions are shared 

 by many, the bulk of his works are theological and 

 metaphysical, but especially theological ; and his re- 

 ligious opinions were confined to an extremely small 

 class of persons. Indeed it may be questioned if he was 

 not in several respects the only person who held his 

 peculiar faith upon all points. 



It happened, fortunately, that when he went to 

 reside at Leeds in care of the Mill-Hill Chapel, 

 his house immediately adjoined a common brewery, 

 and this led him to make experiments upon the fixed 

 air copiously produced during the process of ferment- 

 ation. It must be observed, that long before this time 

 the great step had been made by Black, of ascertaining 

 that there are other permanently elastic fluids than our 

 atmosphere, and which have properties wholly different 

 from it. Cavendish, too, had very recently subjected 

 both fixed and inflammable airs (carbonic acid and 



* Edited by the affectionate care of an able and worthy man, Mr. 

 Towell Rutt. 



