Correct spelling for the English word "fortoin" is [fˈɔːtɔ͡ɪn], [fˈɔːtɔɪn], [f_ˈɔː_t_ɔɪ_n] (IPA phonetic alphabet).
Methylenedicotoin, cotoin formaldehyde, CH2(C14H11O4)2; made by the action of formaldehyde on cotoin, occurring as yellow acicular crystals; has been recommended in the treatment of diarrhea in doses of gr. 2-5 (0.13-0.3).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.