VALCKENAER, JAN, son of the above, was successively professor of law at Franeker, Utrecht, and Leyden, and was likewise known as an author. He was a strenuous adherent of the popular party, in opposition to the house of Orange; and he acted a conspicuous part in the public affairs of the eventful era to which he belonged. He became a member of the legislative body of the new republic; and the Batavian directory sent him on a diplomatic mission to Spain. When Bonaparte had divulged his intention of incorporating the kingdom of Holland with the French empire, Valckenaer was despatched to Paris in order to remonstrate against such a measure. His eloquence was, however, ineffectual; and, on his return, relinquishing all connection with politics, he betook himself to a delightful retreat in the vicinity of Haarlem, where he died on the 19th of January 1820, at the age of sixty-two.