1965 Transactions of the Third International Vacuum Congress, Volume 2, Part I documents the proceedings on the Third International Vacuum Congress held in Stuttgart, Germany on June 28-July 2, 1965. This compilation is divided into four sessions. Session 1 focuses on evaporation and thin films, while Session 2 deals with the flow of gases. The components and materials of orthodox vacuum pumps are covered in Session 3. The last session concentrates on pressure measurement and leak detection. The topics discussed include developments in the vacuum deposition of electronic film circuits; bulk sublimation of titanium; transmission probability determination with directed mass motion and with mean free path considerations; measuring the density and direction of gas molecular flow using an ionization detector; and porous metal isolation traps and cryosorbents in vacuum technique. The factors influencing the performance and design of water-cooled condensers; electrode dimensions of the Bayard-Alpert ionization gauge and its sensitivity; and analysis of the changes in Pirani gauge characteristics are also deliberated in this text. This volume is beneficial to students and researchers conducting work on vacuum, including other related subjects such as etymology, electromagnetism, and quantum mechanics.