Thomas worked on the development of ozotype, a pigmented gelatin process that he patented in 1899. Also, he developed the ozobrome method of producing carbon pictures from bromide prints, patented in 1905, which allowed them to be produced in other than daylight.
Publications Books: "Ozobrome" & "Ozotype," Cassell's Cyclopaedia of Photography, 1911, repr. 1973; Lessons in ozotype... Pigmented gelatine printing...pigmented gum printing, 190-? (Ozotype Co.: London); Ozotype, the new carbon printing process without transfer, actinometer or safe edge, Amateur Photographic Lib., no. 20, 1900 (Hazell, Watson & Viney: London). Anthology: Early Photographs & Early Photographers, Oliver Mathews, 1973.
