permanganate bath
A solution of one of the permanganate salts, such
as salts of permanganic acid, potassium
permanganate sodium permanganate, etc., used to
remove stains from paper. Thirty grams of the
permanganate in one liter of slightly warm water
is the usual concentration. The sheets, subsequent
to treatment, are washed under running water until
as much of the purple stain of the permanganate as
possible is removed. Not all of the salt can be
removed by washing; therefore, the sheets are
generally placed in a bath of 1 ounce of sulfurous
acid to 1/2 liter of water until the original
color is restored. The sheets are then washed
again in running water and resized. (198 , 364 )
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