"'New States, of convenient size, not exceeding four in number, in addition to said State of Texas, having sufficient population, may hereafter, by the consent of said State, be formed out of the territory thereof which shall be entitled to admission under the provisions of the Federal Constitution. And such States as may be formed out of that portion of said territory, lying south of 36° 30' north latitude, commonly known as the Missouri Compromise line, shall be admitted into the Union with or without slavery, as the people of each State asking admission may desire. And in such State or States as shall be formed out of said territory north of said Missouri Compromise line, slavery or involuntary servitude (except for crime) shall be prohibited.' "It will be seen that that contains a very remarkable provision, which is, that when States lying north of 36° 30' apply for admission, slavery shall be prohibited in their constitutions. I presume no one pretends that Congress could have power thus to fetter a State applying for admission into this Union; but it was necessary to preserve the principle of the Missouri Compromise line, in order that it might afterward be extended, and it was supposed that while Congress had no power to impose any such limitation, yet, as that was a compact with the State of Texas, that State could consent for herself, that, when any portion of her own territory, subject to her own jurisdiction and control, applied for a constitution, it should be in a particular form; but that provision would not be binding on the new State one day after it was admitted into the Union. The other provision was, that such States as should lie south of 36° 30' min. should come into the Union with or without slavery, as each should decide, in its constitution. Then, by that act, the Missouri Compromise was extended indefinitely westward, so far as the State of Texas went, that is, to the Rio del Norte; for our Government at the time recognized the Rio del Norte as its boundary. We recognized it, in many ways, and among them by even paying Texas for it, in order that it might be included in and form a portion of the territory of New Mexico. "Then, sir, in 1848, we acquired from Mexico the country between the Rio del Norte and the Pacific Ocean. Immediately after that acquisition, the Senate, on my own motion, voted into a bill a provision to extend the Missouri Compromise indefinitely westward to the Pacific Ocean, in the same sense and with the same understanding with which it was originally adopted. That provision passed this body by a decided majority, I think by ten at least, and went to the House of Representatives, and was defeated there by northern votes.