Mr. Cushing said: I hold in my hand several Petitions on the subject of the slave interest in the District of Columbia. One of them, I now present to the House. Upon it, I make the preliminary motion, understood to be necessary in such cases, that it be received; and, in reference to this question, I have some few remarks to submit to the consideration of the House. This Petition prays for the abolition of slavery, and the slave trade, in this District. It is respectful in its terms, being free