A NEGRO ASSAILING A WHITE MAN. An atrocious attempt was made Sunday morning by a free negro named TOM LONG to assassinate E. B. KEEN, Esq., of Pittsylvania, a highly respected citizen and one of the Delegates elect to the Legislature. LONG, it seems, had formed a plan to take his wife and children who are slaves to a Free State. They belonged to an estate the heirs of which were dispersed through sections of Virginia and North Carolina, and Mr. KEEN, at the solicitation of LONG, and with a purely friendly motive, had put himself to the trouble of buying them up and holding them till LONG could make arrangements to pay for them and take them out of the State. Lately the villain returned from Ohio, where, he reported, he had secured a home and completed arrangements for settling with them. Sunday morning, awhile before day, he roused Mr. KEEN from his sleep telling him that one of his children was very sick. Mr. K. immediately arose and taking a decanter of brandy with him, supposed that the nature of the child’s attack might require its use, opened the door, when he was fired upon by LONG, who stood near, the charge striking the decanter, and some oft eh shots entering his body. The wound is painful and serious, though it is not thought dangerous. He immediately closed the door and thus escaped from the hands of the assassin. The decanter probably saved his life. LONG fled, and is doubtless attempting to make his way to a Free State.