Democratic Sentinel, Volume 18, Number 36, Rensselaer, Jasper County, 21 September 1894 — Envelopes. [ARTICLE]

Envelopes.

A safety envelope, to prevent tampering, has been devised. On the flap, the words, “Attempt to open” are printed with a d*uble set of chemicals, the first impressicn containing nutgalls.ar.'d the second green vitriol If the flap be steamed or moistened in any way, the magio printing will appear. ,