Boric Acid (chemical formula H3BO3) is commonly used antiseptic and insecticide. It usually comes in powdered form, which is then mixed with water. It occurs naturally in nature and can be extracted from borax. It is toxic and about 2.5 grams will kill an average adult if it is ingested or inhaled. In addition, long term exposure to low doses can damage the kidneys.
In medicine, boric acid is commonly used in first aid to prevent infection to small cuts and scrapes. In a very dilute solution, it can be used as an eye wash. In powdered form, it can prevent athlete's foot.