Coalville Times | 1900-06-01 | Page 6 | Invisible Inks

intuitu Ink. Dlttolro one fluid ounce of common com-mon oil of vltrol (sulphuric acid) In one pint of toft water, ttlr well, and allow to cool. Wrlto with n clean itcel pen and when dry tbo writing be-cornea be-cornea Invisible. To read tame hold It In front of the lira and the writing will turn black. Writing done with rlct water la Invltlblo when dry, but on the application ot Iodine the writing turni blue. Writing dono with a clean quill pen dlp?bd In onion or turnip Julco Is Invltlblo when dry. To read tamo hold It In front of the flro, or othorwlae heat It, and tho writing will turn brown.