Gen. Butler has introduced a new plough into Virginia. It is a LEGAL plough; and it turns over slavery in that state as handsomely as ever one of Knox's ploughs turned over a field of green sward. "Articles contraband of war," is the name he gives to slaves that come into his camp or into the possession of our troops. Several hundred of the "articles" have run into Fortress Monroe, and are rendering good service; the administration having advised Gen. Butler to keep an account, for the present, of the amount o their labor and of the cost of their keeping. If the "articles" should turn out to be men, it will be very proper for the government to compensate them for the labor they perform; and wherever there is an army, there must necessarily be a great amount of work to be done.

The first "articles" turned up by Gen. Butler's plough, were three slaves belonging to a Col. Mallory, who, when he claimed them, was told that they were "contraband of war;" yet Col. Mallory could have them if he would come into the fort, and in good faith take the oath of allegiance to the Union. Another lot of thirty "articles" belonged to a gentleman of Richmond. He obtained permission to enter the fort, and to ask of Gen. Butler to allow him to convey them back to Richmond. The General told him that they came there of their own accord, and could go away with him if they chose to do so. Their "master," (as he called himself,) asked them if they would go home with him; and they all promptly answered that they much preferred the company of the soldiers to that of their master. The claimant then said he would manumit them all as soon as he got them in Richmond But Gen. Butler told him he could be a party to no bargain of that sort; the "articles" could go or stay as they pleased. Whereupon the gentleman, making a virtue of necessity, emancipated them all upon the spot; and thus it is, that Gen. Butler's law, if the war goes on, will slice up slavery in furrows, as a plough slices the turf, and quietly turn it over and bury it forever.