28 Mayow 



closely involved with the sulphureous, so the same 

 nitro-aerial spirit effervescing in a slower motion 

 with saline-sulphureous particles, changes the saline 

 particles into an acid liquor only after some time has 

 elapsed. And an example of this is to be sought in 

 vitriol when calcined to the entire removal of the 

 acid spirit. For if that vitriol has been exposed for 

 some time to moist air it will be impregnated anew 

 with acid spirit. Indeed, nitro-aerial spirit encounters 

 the metallic sulphur of colcothar in a gentle manner 

 and effervesces with it in an obscure way, whence it 

 is that the saline or metallic particles of the sulphur 

 are brought in the manner aforesaid to a state of 

 fluidity. Certainly we can scarcely imagine any 

 other mode for the formation of the vitriolic spirit 

 in colcothar, for it does not arise in the colcothar 

 immediately after distillation, and we cannot suppose 

 (as has been elsewhere shown) that it is entirely de- 

 rived from the air. 



Further, the acid spirit of which vitriols are 

 composed seems obviously to be produced in the same 

 way. For vitriols are produced from the stone or 

 rather the saline-sulphureous earth usually called 

 Marchasite, and from it on the application of fire 

 the flowers of common sulphur are elicited in con- 

 siderable abundance. But after this earth has been 

 exposed for some time to the air and wet weather and 

 then (as its nature is) has fermented spontaneously, it 

 will be found to be richly impregnated with vitriol. 

 No doubt the nitro-aerial spirit, effervescing with the 

 metallic sulphur of these Marchasites, converts their 

 more fixed part into an acid liquid which, directly it 

 is produced, attacks the metallic particles of the said 

 stone and draws them out and at last coalesces with 

 them to form vitriol. 



