Sympathetic ink

Definitions

  • Webster's Revised Unabridged Dictionary
    • Sympathetic ink a writing fluid of such a nature that what is written remains invisible till the action of a reagent on the characters makes it visible.
    • Sympathetic ink (Chem) See under Ink.
    • ***
Chambers's Twentieth Century Dictionary
    • Sympathetic ink a kind of ink which remains invisible on the paper until it is heated
    • ***

Etymology

Chambers's Twentieth Century Dictionary
O. Fr. enque (Fr. encre)—Low L. encaustum, the purple-red ink used by the later Roman emperors—Gr. engkaustonengkaiein, to burn in. See Encaustic.

Usage

In literature:

You wrote on those certificates in sympathetic ink that fades, I in ink that comes up soon.
"Constance Dunlap" by Arthur B. Reeve
The first page looked as if it had been written over with some sort of sympathetic ink; but not a word could be deciphered.
"Saxe Holm's Stories" by Helen Hunt Jackson
Sympathetic ink had been used, and the papers had been toasted or treated with acids.
"The Book of Dreams and Ghosts" by Andrew Lang
But this was only a blind; the real letters were written in cipher, with sympathetic ink.
"Mr. Fortescue" by William Westall
There are sympathetic inks.
"The Physiology of Marriage, Complete" by Honore de Balzac
Porter, and contained directions for his cruise, written in sympathetic ink.
"The Naval History of the United States" by Willis J. Abbot
Why, it was a miracle, this living flesh and blood that glowed so warmly and sympathetically through the dead mediums of paper and ink!
"Paul and the Printing Press" by Sara Ware Bassett
A great number of sympathetic inks may be obtained by means of reactions known to chemistry.
"Scientific American, Vol. XXXIX.--No. 24. [New Series.], December 14, 1878" by Various
***