Brian Monetti, I took way too many science classes in college!
This specific reaction is something that magicians used to use to impress people (and it is pretty impressive!) An example of a real world use of color changing chemistry is pH indicators. These reactions use a chemical that turns one color in the presence of an acid, and a different color in the presence of a base. These types of reactions have been known for hundreds of years, so are an example of a use of color changing chemistry from the 19th century.
You can even experiment with color changing chemistry to test pH at home. This video describes how you can use cabbage to create an indicator, which you can use on lots of chemicals from the house, such as vinegar or milk. https://www.noodle.com/learn/details/224119/how-to-make-a-cabbage-ph-indicator