Philosophical Character of Dr. Priestley. 29 



department of science, which Dr. Priestly cultivated with such ex- 

 traordinary success; and, still more, for estimating the value of his 

 discoveries, and adjusting his station as an experimental philosopher, 

 the simple narrative, which he originally gave in the order of time, 

 supplies the amplest and the firmest ground-work. 



In every thing that respects the history of this branch of experi- 

 mental philosophy, the writings and researches of Dr. Priestley, to 

 which I have alluded, are peculiarly instructive. They are distin- 

 guished by great merits, and by great defects ; the latter of which 

 are wholly undisguised by their author. He unveils, with perfect 

 frankness, the whole process of reasoning, which led to his discov- 

 eries ; he pretends to no more sagacity than belonged to him, and 

 sometimes disclaims even that to which he was fairly entitled ; he 

 freely acknowledges his mistakes, and candidly confesses when his 

 success was the result of accident, rather than of judicious anticipa- 

 tion ; and by writing historically, and analytically, he exhibits the 

 progressive improvement of his views, from their first dawnings, to 

 their final and distinct development. Now, witbwhatever delight we 

 may contemplate a systematic arrangement, the materials of which 

 have been judiciously selected, and from which every thing has been 

 excluded, that is not esseiftial to the harmony of the general design, yet 

 there can be no question that as elucidating the operations of the hu- 

 man mind, and enabling us to trace and appreciate its powers of in- 

 vention 'and discovery, the analytic method of writing has decided 

 advantages. 



To estimate, justly, the extent of Dr. Priestley's claim to philoso- 

 phical reputation, it is necessary to take into account the state of our 

 knowlege of gaseous chemistry, at the time when he began his inqui- 

 ries. Without underrating what had been already done by Van Hel- 

 mont, Ray, Hooke, Mayow, Boyle, Hales, Macbride, Black, Cav- 

 endish, and some others, Priestley may be safely affirmed to have 

 entered upon a field, which, though not altogether untilled, had yet 

 been very imperfectly prepared to yield the rich harvest, which he 

 afterwards gathered from it. The very implements, with which he 

 was to work, were for the most part to be invented ; and of the mer- 

 its of those, which he did invent, it is a sufficient proof that they con- 

 tinue in use to this day, with no very important modifications. All 

 his contrivances for collecting, transferring, and preserving different 

 kinds of air, and for submitting those airs to the action of solid and 

 liquid substances, were exceedingly simple, beautiful, and effectual. 



