The "Phase Rule in Application to Saturated Salt Solutions" written by I. A. Kablukov, is a unique training manual, which was admitted to publication in 1933. This work, despite its age, remains relevant and interesting for students, graduate students and specialists in chemistry, physics and materials science. In his work, he immerses the reader in the exciting world of thermodynamics and phase transitions, revealing complex concepts through the prism of saturated solutions of salts. The book begins with the basics of thermodynamics, which allows even beginners in this field to master key concepts. However, do not think that it is simple