Chase Manhattan Corp. and J.P. Morgan & Co. reported higher earnings for the third quarter, reflecting a surge in revenue from foreign exchange trading. Chase Manhattan, the nation’s second-largest banking group, said its earnings rose 25% to $283 million. Morgan, ranked No. 4, posted a 7% increase to $234 million. First Chicago Corp., a leading regional bank, said its earnings soared 80% to $111.4 million on a sharp rise in income from its trading and credit card operations.