Ari exchange paper brings us the fol1 'ving, purpoiting to be an extract from Cassius M. Cliy's Truc American. As Mr. Clay has latoly virÃ¼tcd the North, and liad an opportunity of comnnmi ng witfe lealing Whigs, he inay have facilites for prophesylng not posscsscd by AlÃlitionists. Wogive the anide for what it ia worth. Ia Ã¯vfcmng to a s;Cccli of Ilenry Wilson'in the Massachusetis Legislature, Mr. Clay says: "Siace n.Mi.-ing s-,me eftractÃ¡ 'of this oeek the vbple ofit, and the preamblc and resÃ³luttQn?, have come .tp hand - The rosoluÃ¼ons of Mr. Ciilycr, of New YVk, concÃ«fnihg the overthrow of slavefy Ãn the District of Columbia, and this move m the Mrusaehusett's egislature, in addmon to many Qthec evidences too nuincrous to mention, prove w:iat ffieiave tor years foreseen and most ardenllv in 1 O, will sx.n rally on the greal Hncipjes of rLwtene? 0 iyraiÃ¼j Ã³iirf c nghts of man. If not in 1818, in 1852 partfes wil] be, fairly made up uj,on llÃ¼s sole issue The icsult we venture to predict. The majority of the present W hjg party, a large majority of Democrats, and no inconsiderablo "number of the Liberty Party and Garrisonian AboliÃ¼onists, will ultimately unite on some man and Ã©tect kim. SÃavery will be abolishcd in the district. The Ã¨flbrt to introduce Cuba, or California, or Mexico, as slave states, will prove abortive. Thoy may come in, but they will have to come in f ree. The coast-wise slave trade will be abolished. The supreme court be filled, as vacancies occur, with true free bom men, rightly interpreting theconstitution, ia its true spirit of liberty. The south will bluste r, but not dar e to sever Ãhe uniÃ³n. All the grain-growing States will enter on schÃ¨mes of gradual or immediste emancipation. The Ã¯ntemal slave trade will be abolished; the cocstitution changed, taking away slave rcprescntation. The clausc requiring the return of fugitive slavcs will be repealed. Slavery will retire inlo the cotton and siigar regiÃ³n and there die. The republic will be redeemcd, and universal liberty" be spread over this north continent. If this does not happen, then will the slave power increase; Cuba, Mexico and California come in as slave states. The south will return with an iron hand, joined with the commercial and manufacturng interest of the North; the great mass of Americans, north and south, will be educed to real slavery. The south will ecome more and more worn-out, more orrupt, and seek more and more the 1 ansion of the government patronage an 1 fiices of profit, fpjr her broken down arisocracy. Foreign invasiÃ³n, insurrection, and anrchy will come upon us, singly, or in Ã¯ass, and despotism will swallow up Ihin ong-h'ced HeWel], then, we say with Mr. Wilson. et the Whigs raise their colors, "constituonal resistance to the sÃ¯ave power - and he . utter overthrow ofslavery." Ycs, it s our "inevitable destiny;" let it come - ie sooner the bettcr!" The party has o chance fbrbut four Southern States; in xying to gain them, which hereafter will e very doubtful, it will lose New York nd Pennsylvania, and thus lose the battle! Ve say the Wlijg party will never rise xcept upon the battle cry of "cons'tuonal liberfy," if it seeks any other it Jcerves defeat, just as certainly as it will eet it! Ã¼p, then, and to the battle field -"On, Stanley- on!''