Dry plate

Dry plate, also known as gelatin process, is an improved type of photographic plate. It was invented by Dr. Richard L. Maddox in 1871, and by 1879 it was so well introduced that the first dry plate factory had been established. With much of the complex chemistry work centralized into a factory, the new process simplified the work of photographers, allowing them to expand their business.

Gelatin emulsions, as proposed by Maddox, were very sensitive to touch and mechanical friction and were not much more sensitive to light than collodion emulsions. Charles Harper Bennett discovered a method of hardening the emulsion, making it more resistant to friction in 1873. In 1878, Bennett discovered that by prolonged heating, the sensitivity of the emulsion could be greatly increased. George Eastman developed a machine to coat plates in 1879 and opened the Eastman Film and Dry Plate Company, reducing the cost of photography. A competitor of Eastman in the development and manufacture of gelatin dry plates was the architectural photographer Albert Levy.

...
Wikipedia