C 157 ] 



meafure of nitrous air, makes the 

 tube in the moment the tv/o 

 airs come into contact, and, after 

 fome repofe, he moves again the 

 o cf the brafs fcale to the place 

 where the columns of air and water 

 meet, and writes down the degree 

 of the fcale which correfponds with.' 

 the next mark of the glafs tube 

 above the water. After this he lets 

 tip a third meafure of nitrous air, 

 and, after making and repofing as* 

 before, he marks alfo the degree of 

 the fcale correfponding with the 

 next mark of the glafs tube above 

 the water, and thus finim.es the 

 whole operation, if the air exa- 

 mined is common air : for no 

 more diminution of this air would' 

 happen if more nitrous air was 

 added, as three meafures of ni- 

 trous air are fufBcient to faturate 

 3 fully 



