Gold prices slipped Thursday on the Comex division of the New York Mercantile Exchange for the fourth consecutive trading session. The dollar index rose 0.18 percent on the International Exchange to 81.70, while gold gave up $5.30 to $1,657.70 per troy ounce. Silver lost 45 cents to close at $30.47 an ounce. The euro fell to $1.2507 from Wednesday\'s $1.253. Against the yen, the dollar fell to 78.62 yen from 78.71 yen.