A comparison of the intensity of the color. Sodium standard reagent is the great Niagara Falls hotel is a atmospheric acids react Brucine at 100 degrees and then bring the suck at metric wavelength 410 nm.
Homes comparing the color intensity of sodium nitrate is a chemical reaction in the reagent is Brucine acid at a temperature of 100 degrees, then the measured absorption at a wavelength of 410 nm.