Acid–base reaction models as theories that complement each other. For example the current Lewis model has the broadest definition of what an acid and base are, with the Bronsted-Lowry theory being a subset of what acids and bases are, and the Arrhenius theory being the most restrictive. The first scientific concept of acids and bases was provided by Lavoisier in around 1776. Since Lavoisier's knowledge of strong acids was mainly restricted to oxoacids, such as (nitric acid) and (sulfuric acid), which tend to contain central atoms in high oxidation states surrounded by oxygen, and since he was not aware of the true
Fulvic acid only method that the California departments of agriculture will accept when registering a product. California does not recognize fulvic acid as separate substance from humic acid and requires that all label registrations list the content as humic acid only. Until 2017, Oregon also required using this method but has recently switched to the Lamar Method of fulvic acid quantification and now allows the label registration of fulvic acid as a substance apart from humic acid. The Verploegh and Brandvold method (V&B) quantifies both humic and fulvic acid and is a quick, cost effective, and easy test to perform. It does