84 Mayow 



a clear enough proof that air is not so densely enclosed 

 in nitre. 



It is thus evident that the igneo-aerial particles 

 common to nitre and air are not air itself, but only 

 certain very subtle particles which fixed in air and in 

 nitre constitute their more active and fiery part. Indeed 

 it is probable that igneo-aerial spirit is fixed in the saline 

 particles of nitre very much in the same way as in the 

 aerial particles, and that it is in consequence of their 

 being violently torn from both kinds of particles and 

 thrown into violent agitation that fire is produced. 



It will not be difficult to understand from this hypo- 

 thesis of ours why the water ascends in a glass in 

 which a lamp or an animal is enclosed, although air 

 exists in it in the same abundance as before, and there 

 is no reason to suppose' that it has condensed. For 

 no other conception is possible than that the elastic 

 force of the air has been diminished, and that this 

 is due to a certain change wrought in the aerial 

 particles themselves. But what that change should 

 be, which diminishes the elastic force of the air, unless 

 we suppose that the particles from being rigid become 

 flexible, I confess that I do not understand. 



Further, in what has been already said the reason is 

 to be sought why lamp and animal when placed in the 

 aforesaid glass vessels expire even when air in sufficient 

 abundance seems to be contained in them. It must 

 not be supposed here that of the air enclosed in those 

 vessels a part has been entirely consumed while the 

 rest remains unchanged, because if that were so there 

 would be nothing to hinder the animal from still 

 breathing in it. But it must rather be thought that 

 nearly all the particles of the air have undergone some 

 change, and that they have been deprived to such an 

 extent of nitro-aerial particles that the air has become- 



