 As the details of the expedition were worked out, Humboldt said that he would travel to Russia in his own French coach, with a German servant, as well as Gustav Rose, a professor of chemistry and mineralogy.He also invited Christian Gottfried Ehrenberg to join the expedition, to study water micro-organisms in Lake Baikal and the Caspian Sea.Humboldt himself was keen to continue his studies of magnetism of mountains and mineral deposits.