Chap. 6.]' Eudiometer. 401 



mon air, marking the height of the water at every one 

 refpeclively. After this procefs, if three meafures of 

 either nitrous or common air are introduced into the 

 tube, they will caufe the water to fubfide to the third 

 mark ; but if two meafures of common air and one 

 meafure of nitrous air, or one meafure of the common 

 and two of the nitrous air, are put into the tube, they 

 will fill a fpace much fhort of the third mark. When 

 thele two kinds of air come firft in contact, a reddifh 

 appearance is perceived, which foon vanifhes, and the 

 water, which at firft nearly reached the third mark, 

 rifes gradually into the tube, and becomes nearly fta-^ 

 tionary after about two or three minutes, by which it 

 appears, that the diminution takes place in a gradual 

 way. 



Nitrous air is neither foluble in water nor pofTefles 

 any figns of acidity ; for it has not the power of chang- 

 ing the blue colour of vegetables red, unlefs it is mixed 

 with common or dephlogifticated air, by which it ac- 

 quires the true acid character. 



VOL. I. D d 



