The era fostered a unified multiphase approach to heat and mass transport, integrating solid-state conduction, gas diffusion, and gas-surface interactions into a coherent framework. Researchers emphasized common mathematical structures underlying heat conduction, diffusion, and thermal transport, and tied lattice/phonon perspectives to gas-surface interactions to predict composite thermal behavior. Studies of thermophysical properties across temperature and pressure shaped predictive thermodynamics for materials and energy systems, while gas-phase transport, thermodiffusion, isotopic diffusion, and convective phenomena were developed as complementary routes to energy transfer across phases. Historical Significance: The period yielded foundational analytical and numerical methods—boundary-value problem treatment, finite-difference approaches, and moving-boundary conduction (Stefan problems)—that defined practical heat-transfer analysis for engineering and processing. The integrated viewpoint transcended single-phase problems, influencing later multiphase and phase-change heat-transfer theories and teaching, and establishing the standard references and solution strategies that guided decades of research and application.