Cautions in Use of acids are all poisonous and must be labeled " Polsox," and locked up out of the reach of children. They must not be used on colored fabrics, and must be quickly and thoroughly rinsed out as soon as the stain has been re moved. When possible, they should be followed by the use of hyposul phite of soda, ammonia, or other chemical that will neutralize the acid.
Oxalic Acid.—This is the active principle of salts of sorrel. When combined with cream of tartar it is known as salts of lemon. It may be dissolved in one part of boiling water. It is a dangerous poison, and in cer tain quantities will cause death in about ten minutes. It is used for cleaning leather, scouring metals, es pecially brass and copper, and for re moving various stains. It has very much the appearance of Epsom salts, from which it must be carefully dis tinguished.
Use of Oxalic Acid.—Oxalic acid is especially useful in the laundry to re move iron mold, fruit stains, and ink spots produced by the old style iron gall inks. It does not, however, re move ink stains produced by modern writing fluids or blue-black inks com posed of aniline dyes. Oxalic acid may be applied to cotton, linen, wool en, silk, or any ordinary fabric if un colored, but it bleaches colored goods. The color, can, however, in most cases be restored by aqua ammonia. When possible, it is advisable to experiment with a sample of the goods before ap plying oxalic acid to colored articles.
To Apply Oxalic acid may be applied alone, either dissolved in its own bulk of boiling water for a " saturated " solution, or in nine parts of cold water for a " dilute " solution.
Or, as salts of lemon, it may be dis solved in 1 to 10 parts of water, either hot or cold. The action of the acid is increased by heat as in boiling water.
To apply, either wet the spot in water and cover with dry oxalic acid or salts of lemon, or dip the spot into the solution, or apply the solution to the spot with a small brush, sponge, or piece of rag. If the stains are old or have penetrated through the fabric it will be necessary to rub the acid vigorously into the spot and persist patiently until successful. Oxalic acid is also recommended to bleach silk in the proportion of 4 pounds of the acid and 4 pounds of salt to 2 quarts of water for the raw silk, or 2 ounces of oxalic acid and 2 ounces of salt to 6 quarts of water for white silk that has become yellowed from washing.
The latter proportions may be ob served for removing vegetable or fruit stains, should it be necessary to im merse the article in the solution.
As soon as the stain disappears, rinse with clear water, and after wards wash with soapsuds.
Uses of Citric Acid.—This is the acid principle of alum and lemon juice; it is also found in gooseberries, currants, and some other fruits. It is intensely sour, is readily soluble in water, and is used in medicine; in dyeing, to heighten certain colors, and to break up certain coloring com pounds. Citric acid may be used dis solved in slightly more than its own bulk of water for a saturated solu tion, or in 10 or more parts for a dilute solution. It may be applied to white goods or fast-dyed cotton or woolen, by moistening the stain with a solution by means of the finger tips, a small brush, sponge, or rag. Rinse immediately in clear water. It may be used for stains from fruit, iron gall inks, iron rust, or mildew; but for these oxalic or tartaric acids are commonly preferred. In the form of lemon juice, citric acid is a mild but useful agent, and one generally em ployed. With the addition of salt on colored goods it may safely be used on any ordinary fabric. To apply, saturate the spot with lemon juice, and for colored goods cover with dry salt. Expose to direct sunshine and repeat if necessary.
Or apply lemon juice and salt, and steam the fabric over a kettle.
Uses of Lactic Acid.—This is the acid which forms in milk when it turns sour and which is, therefore, contained in buttermilk. It is the presence of this acid which causes buttermilk to be employed in the proc ess of bleaching linen. Sweet milk, sour milk, and buttermilk are all recommended for the treatment of stains in fabrics, the action being strong in proportion as the liquid sours with age. Hence, when stains are fresh they may be removed by dipping immediately in warm milk; but when they are more stubborn, they may require soaking in butter milk for some time. The addition of common salt increases their effective ness. This is a simple and useful means of treating ink stains from iron-gall inks, tea stains, red-wine stains, and fruit stains, especially when fresh. Sour buttermilk also erases mildew. Wet or soak the arti cle in fresh or sour milk or butter milk, cover with common salt—which contains chlorine, a powerful bleach ing agent—and expose to sunshine in the open air.