Provide some strong chloride of lime, soak in it strips of printed
cotton; take them out, dry them, and you will find them very white,
but very rotten, slitting and dropping into holes upon the slightest
touch.
The dazzling whiteness of paper is caused by bleaching it with chloride
of lime. Thus, if you write on printing paper with common ink, it will
fade, because the chloride will destroy the colouring matter of writing
ink. It will not, however, change printing ink, as that owes its
blackness to charcoal, which is a singularly permanent substance. Blot
over a printed page with common writing ink, wash it with chloride of
lime, when the blots will disappear, and leave the printing unchanged.