Correct spelling for the English word "tachiol" is [tˈakɪˌɒl], [tˈakɪˌɒl], [t_ˈa_k_ɪ__ˌɒ_l] (IPA phonetic alphabet).
A trade name for silver fluoride; said to be powerfully germicidal in solutions of 1-100,000 or even weaker.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.