sentences:  Factors like the grain size of gunpowder and the time it sat in the spirit impact the dissolution of potassium nitrate and therefore what would be defined as 100 proof.However, the gunpowder method is significantly less variable than the burn-or-no-burn method and 100 proof defined by it is traditionally defined as 57.15% ABV.By the end of the 17th century England had introduced tests based on specific gravity for defining proof.