Please. Sure, there are some passing incidental references to slavery in Mississippi's Declaration of Secession (the subject could hardly be ignored because it was in all the papers at that time), but if you can try to read between the lines (the way it was intended to be read), you can see that it really just takes up where the Declaration of Independence left off.
Here, try to read it again, with fresh eyes.
http://americancivilwar.com/documents/causes_mississippi.html
And try for once to appreciate the subtleties and nuances that were carefully designed for posterity.
Some passing reference?????
"Our position is thoroughly identified with the institution of slavery - the greatest material interest of the world. Its labor supplies the product, which constitutes by far the largest and most important portions of commerce of the earth. These products are peculiar to the climate verging on the tropical regions, and by an imperious law of nature, none but the black race can bear exposure to the tropical sun. These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin."