The Devil's Milkshake is a simple, yet interesting chemistry experiment that fits well as a Halloween demo.
Simple chemical tests are described that can indicate the presence of certain metals in coins. A wide variety of chemical concepts are involved. The experiments described are a natural fit for the 2019 National Chemistry Week theme of "Marvelous Metals!"
The solution to "Chemical Mystery #16: A Red, White, and Blue Chemistry Trick for You!" is presented. How this experiment can be used as a springboard to carry out a simple quantitative analysis of salt solubility is also discussed.