[ I2 4 ] 



by the addition of fomething, or 

 by becoming deprived of fomething 

 extraneous to its own original firn- 

 ple nature ; we can no more be 

 furprized to find, that the conftitu-r 

 tion of the atmofphere remains fel* 

 dom a whole day the fame, and that 

 the degree of falubrity is continually 

 changing. Indeed, in the courfe of 

 three months, which I fpent in my 

 folitary retirement, I fcarce found 

 the degree of falubrity of the com- 

 mon air juft the fame .during two 

 days. 



Thofe who are not yet acquainted 

 with the accuratenefs of AbbeFon- 

 tana's new 'Eudmmeter^ will be much 

 Inclined to believe, that the appear- 

 ance of fuch continual variations 

 is more owing to the imperfection 

 of the method of exploring the air, 

 than to the real changes happening 



in 



