A compound of boron with sodium and oxygen, is obtained chiefly from Tuscany, and is found also in Tibet, China, Nevada, and California. It is used in soldering gold and other metals, and in the arts as a flux. Dyers use it to give a gloss to silks. It is employed also in medicine, and as a cosmetic. It is valuable as an insecticide, being fatal to roaches, and is much used in preserving meat, fish, butter, and milk.