Humboldt and American Slavery.

--The following, from a letter addressed lately by Alexander Von Humboldt to Julius Froebel, a German author of some distinction, and formerly a member of the Parliament at Frankfort, may not be without interest to some of our readers, partly from the question of slavery it alludes to, and partly from the noble image it exhibits of the undying earnestness of purpose in that "old man eloquent:"--"I should like to live long enough yet to see your book On the Political State of America, with which you are engaged.

May you continue to brand that shameful leaning to slavery, and that imposture about introducing negroes who are said to become free, and which is a means to encourage those negro hunts in the interior of Africa.

What horrors one is obliged to witness, if one has the misfortune of living from 1789 to 1858.

My book against slavery has not been prohibited in Madrid, yet in the United States, which you call 'the republic of gentlemen,' it could only become saleable by the omission of all that concerns the sufferings of coloured people who, according to my political views, are fellow-men entitled to enjoy any amount of freedom.

I lead an industrious life, chiefly at night, being much worried by an ever-increasing and mostly uninteresting correspondence.

I exist joylessly, in my 89th year, since of so many things towards which I have striven ever since my early youth, and with ever equal warmth, so very little has been fulfilled."