40 On Dr. MUdnirs Theory 



a very peculiar and deftruftive acid. Such an acid poifon, 

 he became perfuaded, had deprived Mr, Hewfon, Dr. Walfli, 

 Mr. Jones, and other difiecilors, of their lives, hy being ad- 

 mitted to a furface denuded of I'kin. Dr. Latham's fad of 

 the fcrvant polfoned by touching an agnail on his finger with 

 the fiefli of a putrid hare which he v.as (kinning, is of the 

 fame kind. Imnicriion of thefe carcafes in flrong folutions 

 of alkaline falts^ or the mere fprlnkling them with pot-afli 

 or foda, would, he thought, have prevented thofe unpleafant 

 accidents. 



In fuch cafes the prccluft formed by the chemical union 

 of azote with oxygen, mingled with more or Icfs of water, 

 and exifting in a liquid form, polfoned only when the parts 

 of a living animal were brought into contact with it, as it 

 befpreads the furface which produced it. But Dr. Mitchill 

 was convinced, that, in higher temperatures, v/hen the furface 

 of the earth was heated to ii6 degrees, and even to 130 of 

 Fahrenheit's fcale, this liquid poifon took on occafionally a 

 vaporlfic or aerial form, and was copious enough fometlmes 

 to taint or infe6l a chamber, a houfe, a neighbourhood, or 

 even a city. In the former cafe it injured none but thofe 

 who meddled with it, in the fpots where it was produced ; 

 in the latter it rofe into the atmofpherc, and fallied forth in 

 quefl of prey, to diftances indefinitely remote. 



About this period of the inquiry Dr. Mitchill made au 

 excuriion through a part of the State of New York, in con- 

 fequence of an appointment from the Society for promoting 

 Agriculture, Arts and Manufaftures, to explore the natural 

 produftions of the country, and efpecially to determine 

 whether any mines of coal cxlfted in the neighbourhood of 

 Hudfon's River. It did not appear that any confiderable 

 quantities of that article of fuel were to be foynd; but it was 

 afcertained, in the courfc of the expedition, that, in fome of 

 the manufaftories, where the alkaline fait of burnt-wood is 

 extradled to form the pot-afli and pearl-afli of commerce, 

 t'.iere was enough of oxygenated azote in the atmofpherc to 



combioG 



I 



