[ 176 ] 



again fuppofe, that the nitrous air 

 employed was fo weak, that, infread 

 of three meafures, fix were required 

 before the faturation was fully com- 

 pleated, and that thus the remain- 

 ing column of air in the great tube 

 occupies 60 Q , inftead of 308, fub- 

 divifions ; we ill all find that the re~ 

 fult will be. jult the fame ; that is 

 to fay, that,. by fubtrac~ting the 608 

 parts remaining from the 800 parts 

 of both airs employed in the expe- 

 riment, there will be found ex- 

 actly 192 fub-divifions deitroyed ; 

 and that thus in both cafes the ac- 

 curate falubrity of the air is afcer- 

 tained. If fuch bad nitrous air 

 was only at hand as was jufl now 

 fuppofed, it follows, that a longer 

 tube ought to be employed. 



This obfervation, which I owe 

 entirely to Abbe Fontana, is in my 



opinion 



