Hence, in 1882, after the introduction of these arguments by Clausius and Gibbs, the German scientist Hermann von Helmholtz stated, in opposition to Berthelot and Thomas’ hypothesis that chemical affinity is a measure of the heat of reaction of chemical reaction as based on the principle of maximal work, that affinity is not the heat given out in the formation of a compound but rather it is the largest quantity of work which can be gained when the reaction is carried out in a reversible manner, e.g., electrical work in a reversible cell. The maximum work is thus regarded as the diminution of the free, or available, energy of the system (Gibbs free energy "G" at "T" = constant, "P" = constant or Helmholtz free energy "A" at "T" = constant, "V" = constant), whilst the heat given out is usually a measure of the diminution of the total energy of the system (Internal energy). Thus, "G" or "A" is the amount of energy “free” for work under the given conditions.