Peace of Napoleon

I reread PEACE recently and have a question. (Well, I've got a lot of questions, of course, but one in particluar.) On page 2 of the Orb edition Weer mentions knowing why Napoleon had one hand thrust into his waistcoat, having read it, possibly in "Ludwig's biography of him." But when he told people he found that "the innocent remark invariably offended." Does anyone in this group know what Wolfe is referring to here? And is there really biography of Napoleon by a man named Ludwig? Thanks for any help. William Ansley