BILLACH, a circle in the Austrian province of Laybach and Trieste. It is a woody district, extending over 2091 square miles, or 1,338,240 acres. It is rich in mines, producing some gold, much lead, quicksilver, alum, antimony, iron, and copper. The inhabitants in 1817 were 111,850, of whom 17,000 were Lutherans, and the remainder Catholics. The capital of the circle is a city of the same name on the river Drave. It contains about 5000 inhabitants, is a manufacturing town, and enjoys much trade from being on the high road to Italy. It is in long. 13. 47. E. lat. 46. 35. N.