From Buenos Ayres.
--The latest intelligence from that place is up to the 14th of February. The news of the terrible massacre at San Juan, previously reported, is confirmed. The number of men butchered in cold blood after the capture of that place is given at six hundred. At Buenos Ayres the most terrible excitement prevailed in consequence, and revenge was the sentiment of all parties. The General Government of the Argentine Confederacy has approved the action of Colonel Saa, the commander at the slaughter, by making him a present of two thousand ounces of gold. In the course of a few months the old feud between the Federalists and the Unitarians is expected to break out again. The former party is mainly confined to the upper provinces. The Governor of Buenos Ayres had addressed a letter to the Federal Administration, demanding an explanation in reference to the San Juan affair — an event that is charged upon the intermeddling conduct of that province itself, which is but poorly prepared for war. It was supposed that Urquiza would take command of the Federal troops, in case the two parties should come to blows.