Boric acid powder is used as an insecticide to control roaches, silverfish and ants. The acid attacks the insects' gastrointestinal tracts and abrades their exoskeletons. Boric acid powder also is used to kill algae and weeds, preserve wood, and eliminate wet and dry rot.
Boric acid powder can be added to soil if it is deficient in boron. However, too much boron in the soil is toxic for plants, and boric acid powder applied directly to plants dries them out. It deodorizes garbage cans and toilets, and it's also used in leathermaking and to regulate the pH of swimming pools.
A solution of boric acid powder can treat minor eye and external ear infections. It's also used as an eye wash to cleanse the eye of pollution and irritants. This solution works for both humans and pets. Boric acid powder can be applied to feet to reduce sweating and cut down on the risk of athlete's foot. It also can be used to treat vaginal yeast infections. People use boric acid powder in solution to ease minor burns and cuts.
Boric acid is derived mainly from borax, a mineral that forms stubby, white crystals. Large masses of these crystals are generally found around saline lakes and salt pans in deserts.