Drude's theory of metals, presented in the first part, proposes that the electrical conductivity of metals is due to the movement of electrons (or electric nuclei), which are small particles carrying electric charge. Unlike electrolytes, metals do not involve a measurable mass transport during electrical conduction. Drude argues that the concept of "ions" should be reserved for aggregates of electrically charged particles with ponderable mass, while electrons should be considered as massless particles. He notes that the apparent mass of an electron depends on its charge and spatial extent, and that the self-induction of electrons plays a role in their motion. Drude also addresses the difference between metals and electrolytes, noting that in metals, no mass transport occurs, and the metal is not altered by electric currents. He criticizes the idea of electron charge transfer as being unphysical and instead proposes that electrons in metals are of two types (positive and negative) but identical in mass and charge. This would explain why no mass transport occurs in metals, unlike in electrolytes. Drude further discusses the optical properties of metals, noting that bound electrons (those attached to atoms) are necessary to explain the optical behavior of metals. He also revisits the theories of electrical conductivity, thermal conductivity, and other related phenomena from the perspective of electron theory. He emphasizes that the number of free electrons in a metal is crucial for understanding its properties, and that the theory must account for both free and bound electrons. Drude introduces the universal constant α, derived from kinetic gas theory, and uses it to calculate the thermal and electrical conductivity of metals. He shows that the ratio of thermal to electrical conductivity (the Wiedemann-Franz law) is proportional to absolute temperature. He calculates the value of α based on gas laws and the Loschmidt number, and compares it with experimental data. Drude also discusses the Thomson effect, which is the heat generated when an electric current flows through a temperature gradient. He derives an expression for the Thomson effect, showing that it depends on the temperature gradient and the properties of the electrons in the metal. He notes that deviations from the Wiedemann-Franz law can occur when the number of free electrons depends on temperature, and that this is consistent with experimental observations. Finally, Drude considers the contact potential difference between two metals in contact, noting that the potential difference arises to maintain equilibrium between the two metals. He discusses the role of electron diffusion and the potential difference that arises due to the different distributions of electrons in the two metals. He concludes that the theory provides a consistent explanation for various electrical and thermal phenomena in metals, and that further experiments are needed to confirm the predictions of the theory.Drude's theory of metals, presented in the first part, proposes that the electrical conductivity of metals is due to the movement of electrons (or electric nuclei), which are small particles carrying electric charge. Unlike electrolytes, metals do not involve a measurable mass transport during electrical conduction. Drude argues that the concept of "ions" should be reserved for aggregates of electrically charged particles with ponderable mass, while electrons should be considered as massless particles. He notes that the apparent mass of an electron depends on its charge and spatial extent, and that the self-induction of electrons plays a role in their motion. Drude also addresses the difference between metals and electrolytes, noting that in metals, no mass transport occurs, and the metal is not altered by electric currents. He criticizes the idea of electron charge transfer as being unphysical and instead proposes that electrons in metals are of two types (positive and negative) but identical in mass and charge. This would explain why no mass transport occurs in metals, unlike in electrolytes. Drude further discusses the optical properties of metals, noting that bound electrons (those attached to atoms) are necessary to explain the optical behavior of metals. He also revisits the theories of electrical conductivity, thermal conductivity, and other related phenomena from the perspective of electron theory. He emphasizes that the number of free electrons in a metal is crucial for understanding its properties, and that the theory must account for both free and bound electrons. Drude introduces the universal constant α, derived from kinetic gas theory, and uses it to calculate the thermal and electrical conductivity of metals. He shows that the ratio of thermal to electrical conductivity (the Wiedemann-Franz law) is proportional to absolute temperature. He calculates the value of α based on gas laws and the Loschmidt number, and compares it with experimental data. Drude also discusses the Thomson effect, which is the heat generated when an electric current flows through a temperature gradient. He derives an expression for the Thomson effect, showing that it depends on the temperature gradient and the properties of the electrons in the metal. He notes that deviations from the Wiedemann-Franz law can occur when the number of free electrons depends on temperature, and that this is consistent with experimental observations. Finally, Drude considers the contact potential difference between two metals in contact, noting that the potential difference arises to maintain equilibrium between the two metals. He discusses the role of electron diffusion and the potential difference that arises due to the different distributions of electrons in the two metals. He concludes that the theory provides a consistent explanation for various electrical and thermal phenomena in metals, and that further experiments are needed to confirm the predictions of the theory.