celluloid, the first synthetic plastic material, developed in the 1860s and 1870s from a homogeneous colloidal dispersion of nitrocellulose and camphor. A tough, flexible, and moldable material that is resistant to water, oils, and dilute acids and capable of low-cost production in a variety of colours, celluloid was made into toiletry articles, novelties, photographic film, and many other mass-produced goods. Its popularity began to wane only toward the middle of the 20th century, following the introduction of plastics based on entirely synthetic polymers. Some historians trace the invention of celluloid to English chemist Alexander Parkes, who in 1856 was granted