LIFE of Dr BLACK. 105 



An elaflic fluid, indeed, of the fame qualities, has been fmce 

 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 chemifts, being led by their experiments to con- 

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

 ■with vital air, have laid afi.de the appellation of Fixed Air, and 

 have fubftituted that of Carbonic Acid Gas in its ftead. 



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

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

 portant, had been comparatively fmalL The compofition of the 

 atmofphere, the diftindlion of vital and mephitic air, the efFedls 

 of refpi ration, and the conjedlural theories of combuftion and 

 animal heat, might have remained unknov^n. 



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

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

 count of their part in tliefe 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 fads, 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, tliat atmofpheric air is not homoge- 

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

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

 which, without being fo diluted, would be too intfinfe 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. 



