The Mountain Nymph, Sweet Liberty by Julia Margaret Cameron

Coating the Plate, from Gaston Tissandier, A history and handbook of photography, ed. and trans. J. Thompson (London, 1876), 109

Cameron had to move quickly and carefully when making and exposing collodion-on-glass negatives, since the sensitized plates had to remain damp for the duration of the process. Collodion is a highly flammable solution made by dissolving cellulose nitrate (gun cotton) in ether and alcohol. A solution of salt was added to the collodion. Cameron poured the collodion, which had the consistency of very thin syrup, from a bottle onto a clean glass plate. She tipped the plate as she poured, striving for a smooth, even distribution, and then dipped the plate in silver nitrate, which made the collodion light-sensitive.