Summarize Griffin’s explanation of his becoming invisible.

After dropping out of med school, Griffin discovered a formula of pigments that lowers the refractive index of a substance, allowing light to pass through it rather than being reflected or refracted. After experimenting with pigments for three years, he he found a way to manipulate animal tissue so that it looks transparent.

Griffin explains how he had found lodging in a boarding house on Great Portland Street. He finally made a piece of cloth disappear, then he tried his process on a stray cat. This was only partly successful.