The book I am reading, Smith Van Ness Abbott has several figures of Pressure vs Composition for Vapor Liquid Equilibrium of a Binary system. It often includes a dashed straight line to represent Raoult's Law. What confuses me is that only the liquid phase ( P-x1 ) is said to exhibit deviations from the Raoult's Law-the dashed line. I have uploaded two pictures. In Figure 10.11, P-x1 is a straight line, characteristic of Raoult's Law. However, P-y1 is not a straight line. Figure 12.5 is a graph of real VLE behavior. The P-x1 curve deviates from the dashed line, as does the P-y1 curve, which also was nonlinear in Raoult's Law system. From the book's description, only the liquid phase deviates from Raoult's law. And in a system obeying Raoult's Law, only the liquid phase has a linear P-x1 behavior. Am I understanding this correctly?