They are both particular cases of the Gibbs Equations ( Josiah Willard Gibbs ) : the Kelvin equation is the constant temperature case .
The Gibbs -- Thomson equation is the constant pressure case .
They are both particular cases of the Gibbs Equations ( Josiah Willard Gibbs ) : the Kelvin equation is the constant temperature case , and the Gibbs -- Thomson equation is the constant pressure case .