We generalize results of Rosenlicht to give a necessary and sufficient condition for when order one differential equations of the form $D(x) = f(x)$ (where $f$ is a rational function over an arbitrary differential field) is orthogonal to the constants. The proof relies on Rosen's theory of $\tau$-forms and differential Galois theory. We will also explain the connection between the notion of orthogonality to the constants and algebraic general solutions. Portions of this work are joint with Joel Nagloo and Ngoc Thieu Vo.