On Sal Nitrum and Nitro- Aerial Spirit 29 



But indeed iron rust also, which has a vitriolic 

 nature, seems to be produced by the action of 

 nitro-aerial particles meeting with the metallic 

 sulphur of iron, for the saline particles of the 

 iron when brought into a fluid condition in the 

 manner aforesaid corrode and dissolve its metallic 

 particles ; and from these combined, rust or a sort 

 of imperfect vitriol is produced — very much as if 

 the iron had been smeared with some acid liquid. 



It should also be noticed that acid salt or sourness 

 is produced by the action of nitro-aerial spirit not 

 only in solids but also in liquids. For it is not 

 enough to say that the acidification or the fluidity 

 of the salts arises from this, that saline particles which 

 before had been mutually hidden by the intervention 

 of the other particles, afterwards, the bond of the 

 mixture being loosed, flow together and spread 

 themselves out through the whole structure of the 

 substance, and that when these gain dominion 

 sourness is produced in the mixture as some have 

 imagined. For we must suppose that all the salts 

 of the liquid were even from the first diffused 

 through its whole mass, since they were dissolved in 

 the liquid. It should rather be maintained that 

 the souring of liquids is caused by the change of 

 their fixed salt into an acid salt, a result which 

 is probably due to the action of nitro-aerial spirit. 

 For liquids abounding in fixed salt and sulphur, such 

 as French wine and strong ale, acquire acidity 

 from lengthy fermentation. Moreover, the fermenta- 

 tion of the liquids consists in the effervescence of 

 nitro-aerial particles, whether contained in the liquid 

 or entering from without, with the saline-sulphureous 

 particles of the liquid, as I shall endeavour to show 

 below. And hence it is that the saline particles of 



