You are fortunate, as the history of the 125th Illinois Infantry is available online. Click on this link and you can view the book in a number of formats.

http://www.archive.org/details/125thregimentill00roge

If you view it online I'd suggest the "Flip Book". If you download and save it to read on your PC or to printout, I'd recommend the "PDF" format.

You'll find a reference to Isaac N. Adams on page 201, where is states he died of wounds in Chattanooga, TN, Nov. 4, 1864.

Jim Martin