V.] JOSEPH PRIESTLEY. 99 



The first outcome of Priestley's chemical work, 

 published in 1772, was of a very practical character. 

 He discovered the way of impregnating water with an 

 excess of "fixed air," or carbonic acid, and thereby 

 producing what we now know as "soda water"- a 

 service to naturally, and still more to artificially, 

 thirsty souls, which those whose parched throats and 

 hot heads are cooled by morning draughts of that 

 beverage, cannot too gratefully acknowledge. In the 

 same year, Priestley communicated the extensive 

 series of observations which his industry and ingenuity 

 had accumulated, in the course of four years, to the 

 Eoyal Society, under the title of " Observations on 

 Different Kinds of Air" a memoir which was justly 

 regarded of so much merit and importance, that the 

 Society at once conferred upon the author the highest 

 distinction in their power, by awarding him the Copley 

 Medal. 



In 1771 a proposal was made to Priestley to ac- 

 company Captain Cook in his second voyage to the 

 South Seas. He accepted it, and his congregation 

 agreed to pay an assistant to supply his place during 

 his absence. But the appointment lay in the hands 

 of the Board of Longitude, of which certain clergymen 

 were members ; and whether these worthy ecclesiastics 

 feared that Priestley's presence among the ship's com- 

 pany might expose his Majesty's Sloop Resolution to 

 the fate which aforetime befell a certain ship that 

 went from Joppa to Tarshish ; or whether they were 

 alarmed lest a Socinian should undermine that piety 

 which, in the days of Commodore Trunnion, so 



