On Muscular Motion and Animal Spirits 277 



formed inside the bodies of animals — in that chemical 

 workshop of nature — into volatile salts. And the 

 same thing is indicated by the fact that if plants 

 which contain no volatile salt are allowed so far to 

 putrefy until they have been converted into worms, 

 then at last volatile salt can be obtained in abundance 

 from them by distillation. 



As to the mode in which the fixed salts of the 

 food are volatilised, it is probable that the various 

 digestions and fermentations taking place in the 

 bodies of animals contribute in no small degree to 

 the volatilisation of the salts : indeed we may hold 

 that the spleen is the chief workshop in which 

 the nitrous salts of the food are worked up into 

 volatile salts. For, indeed, it is to be observed that 

 when vegetables are burned, their nitrous salts are 

 volatilised ; and they flying off along with sulphureous 

 particles, somewhat dried up, constitute the soot. 

 And soot abounds in volatile salt, although the 

 vegetables which, when burned, yield it, before their 

 deflagration, contained only fixed or nitrous salt. 

 And, as when nitre and sulphur are mixed together 

 and burned, as in gunpowder, it is probable that the 

 fixed salt, of which nitre in part consists, is volatilised 

 during the deflagration and flies off" in the vapours ; 

 for otherwise the fixed salt of the nitre would remain 

 after its combustion, for in the deflagration of nitre, 

 the nitro-aerial particles which it contains, set in very 

 swift motion by means of the ignited sulphureous 

 particles, most finely break up the saline particles 

 with which they were previously firmly combined, 

 and, as is probable, makes them volatile. 



But if indeed the exceedingly impetuous and igneous 

 effervescence of the nitro-aerial and sulphureous 

 particles suffices to volatilise in an instant the fixed 



