LIFE of Dr BLACK. 105 



An elaftic fluid, indeed, of the fame qualities, has been fince 

 obtained from various fources ; from vinous fermentation, from 

 the earth itfelf, laid open in grottos or fiffures, from mineral 

 fprings, from the breathing of animals, and from the combuftion 

 of charcoal. This air is found to have the properties of an acid ; 

 and the French chemifls, being led by their experiments to con- 

 fider it as produced by the union of the principle of charcoal 

 with vital air, have laid afide the appellation of Fixed Air, and 

 have fubftituted that of Carbonic Acid Gas in its ftead. 



If the refearches to which the obfervation of fixed air gave oc- 

 cafion, had terminated here, the acceffion to fcience, though im- 

 portant, had been comparatively fmalL. The compofition of the 

 atmofphere, the diftinction of vital and mephitic air, the effects 

 of refpiration, and the conjectural theories of combuftion and 

 animal heat, might have remained unknown. 



Here, however, no mean progrefs has been made, and names 

 too numerous to be recited in fuch minutes as thefe, will, on ac- 

 count of their part in thefe ftudies, go down, with well-merited 

 luftre, to future ages. Nations may hereafter contend for the 

 honour of fuch difcoveries as were made by Lavoisier, Priest- 

 ley and others *, not merely of fingle or infulated facts, but of a 

 magnificent order exifting in nature, for the continuance of ve- 

 getation and animal life. Even France and England, though 



O 2 rich 



* To Lavoisier we owe the difcovery, that atmofpheric air is not homoge- 

 neous, but compofed of nearly three parts of azot, which is not of any effeft in 

 refpiration, otherwife than as it dilutes the remaining fourth part, or the vital air, 

 which, without being fo diluted, would be too intenfe either for the purpofe of ani- 

 mal refpiration or of common fire. 



To Priestley we owe the difcovery, that the well known corruption or wafte 

 of vital air, in the burning of fuel, or the refpiration of animals, is repaired in 

 the vegetation of plants. 



If in fcience there might be any choice of truths, I would willingly hope that 

 the decompofition of water may be found a miflake. 



