SIR,--We, the undersigned, citizens of color, regarding you as the purest and best friend of our race, admiring your consistent course in the United States Senate and elsewhere as the special advocate of our rights, and believing that your counsel at this critical juncture in the period of our citizenship would be free from personal feeling and partisan prejudice, have ventured to request your opinion as to what action the colored voters of the nation should take in the Presidential contest now pending. The choice of our people is now narrowed down to General Grant or Horace Greeley. Your long acquaintance with both and your observation have enabled you to arrive at a correct conclusion as to which of the candidates, judging from their antecedents as well as their present position, will, if elected, enforce the requirements of the Constitution and the laws respecting our civil and political rights with the most heart-felt sympathy and the greatest vigor. We hope and trust you will favor us with such reply as will serve to enlighten our minds upon this subject and impel our people to go forward in the right direction. Our confidence in your judgment is so firm, that, in our opinion, thousands of the intelligent colored voters of the country will be guided in their action by your statement and advice. Hoping to receive a reply soon, we have the honor to be, With great respect, Your obedient servants, A. T. AUGUSTA, M. D. SAMUEL PROCTOR. DAVID FISHER, sr. J. J. KETCHUM. JNO. H. SMITH. CHAS. N. THOMAS. EDWARD CRUSOR. WM. H. SHORTER. WM. H. A. WORMLEY. HENRY HILL. WILLIAM P. WILSON. FURMAN J. SHADD. R. W. TOMPKINS. GEO. D. JOHNSON. JOHN H. BROWN. CHRIS. A. FLEETWOOD. HENRY LACY. CHAS. F. BRUCE. W. H. BELL. DAVID FISHER, jr. J. L. N. BOWEN. DAVID KING. JACOB DE WITTER. WM. POLKENY. HON. CHARLES SUMNER. LETTER. WASHINGTON, July 29, 1872. GENTLEMEN AND FELLOW-CITIZENS:-- If I have delayed answering your communication of July 11th, which was duly placed in my hands by your committee, it was not because the proper course for you seemed doubtful, but because I wished to reflect upon it and be aided by information which time might supply. Since then I have carefully considered the inquiries addressed to me, and have listened to much on both sides; but my best judgment now is in harmony with my early conclusion.