Democratic Sentinel, Volume 22, Number 18, Rensselaer, Jasper County, 7 May 1898 — IODINE AS A DETECTIVE. [ARTICLE]

IODINE AS A DETECTIVE.

It Shows if .Paper Has Been Moistened or Robbed. Another use has been for the vapor of iocUne. This is the discovery of alterations iu manuscripts, says Odds and Ends. Professor Bruylats of Louvain noticed that when a sheet of paper which had been sized and finished was moistened, and, after being thoroughly dried, exposed to the vapof of iodine, the part which had been moistened became violet, while the unmoistened portions became brownish yellow. It appears that when a manuscript lias been altered, both the nature and extent of the alteration can be determined by the use of iodine vapor. Those parts which have been rubbed become brownish on exposure, and" when the rubbed part is subsequently moistened, it becomes blue, the depth of the color depending on the length of time that the exposure bad been allowed to proceed. The process is believed to be due t« the well-known fact that when iodine is put on starch the starch becomes blue, and the difference in the ttot is dependent on the fact that a portion of the starch which is contained in the size has been removed in the process of the alteration of the manuscript. The same process will reveal the extent of pencil marks which have been erased by rubbing. The iodine vapor brings out the lines which have been traced by the pencil point disturbing the surface of the paper, even though the nibbing has been so carefully d*» that it has not removed any of the suP face of the paper itself.