For cleaning tile mosaic floors, use muriatic acid (spirit of salts) diluted with water (the requisite strength may be found by trial), well scrubbing the floor with an old brush, and washing off with clean water. For marble mosaic floors, use a bleach consisting of, say, 71b. of American potash dissolved in a pailful of water, and made into a paste by adding whiting, or, better still, newly slaked lime. Apply this like whitewash with an old brush to the floor. Let it remain on for a day or two, and then wash off with clean water. Repeat the application until the stains are removed. The hands must be protected when using the bleach, as the potash is so caustic as to be dangerous to fingers and nails. If any of the liquid gets on the hands, they should be at once well washed in water containing a few drops of vinegar or acid to neutralise the alkali.