Both Houses of CONGRESS are still engaged in debating the various questions growing out of slavery. In the House a bill for the immediate admission of California is pending, and debate upon it has been closed; but a decisive vote is evaded from day to day. Whenever that can be reached, there will probably be found to be a majority in favor of the bill. In the Senate a bill is pending which provides: 1. For the admission of California; 2. For organizing territorial governments for New Mexico and Utah, without any provision on the subject of slavery; and 3. For paying Texas a sum not specified, for relinquishing her claim to a part of New Mexico. The bill has been very fully and very ably discussed, and votes have been taken upon a great number of amendments to it, the most important of which was one prohibiting slavery forever from these territories. This was offered by Senator Seward of New York, and rejected, 33 to 23. It is believed that the final vote will be taken upon the hill before many days: the chances are in favor of its passage. The attention of Congress has been so thoroughly occupied with these bills, that no other business of any importance has been transacted or even entertained. The general subject of slavery, which gives to them all their interest, has entered largely into the public discussions of the month. Mr. WEBSTER has written a letter to the citizens of Newburyport, Mass., upon the wrong done to the South by refusing to surrender their fugitive slaves, urging the necessity for a more stringent law, and expressing the opinion, that there is nothing, either in the spirit or the letter of the Constitution, requiring a jury trial to determine the question of slavery, when an alleged fugitive is seized. This letter has elicited a reply from Hon. HORACE MANN, of the House, also from Massachusetts, which enforces the contrary opinion, with abundant and vehement rhetoric and cogent argument. Prof. STUART, of Andover, has also published a pamphlet in support of Mr. Webster's views on the general subject.--The convention of delegates intended to represent the slave-holding states, called some months since, met at Nashville, Tenn., on the 3d of June, and adjourned after a session of ten days. Judge SHARKEY, of Mississippi, presided. The attendance was thin, delegates being present from less than half the districts interested, and they having been elected by less than a tenth of the popular vote. Resolutions were adopted, affirming the claims of the slave-holding states, and the convention adjourned to meet again six weeks after the adjournment of Congress, then to take such action as the legislation of the present session may render necessary.--A new paper called "The Southern Press" has been established at Washington, for the express purpose of advocating the interests of slavery. It is under the patronage of 57 southern members of Congress, and is intended to abstain