CORNING, N.Y., Oct. 25 -- Corning Inc., citing the industry's high demand for fiber and cable, reported that its profit in the third quarter increased to $254 million, or 28 cents a share compared with $142 million, or 18 cents a share last year. For the three months ended September 30 profits reached $317 million, or 35 cents a share, not including onetime items, the company said. This is an increase compared with $148 million, or 19 cents a share, for the same 1999 period.Sales were $1.9 billion, an increase of 54 percent from &$46;1.25 billion for the third quarter of 1999. Excluding the impact of acquisitions, sales increased 37 percent, the company said. Besides the demand for fiber optics, Corning said sales of components like optical amplifiers and LCD flat-panel display glass more than doubled.