Introducing a new thermodynamically conjugate pair of variables: number of particles and chemical potential. Internal and external chemical potential. Voltmeters measure the total chemical potential. Great class brainstorm on internal voltages in your life. How to get a theory named after yourself. Spins in a magnetic field. Why atmospheric pressure falls off with height, hiking in high altitude, and how to solve that deuterated Kool-Aid problem we talked about in Lecture 6. Lead-Acid batteries and your car.