IN your notice on the late Karl Friedrich Mohr there is no mention made of one of his most remarkable works, “Die Geschichte der Erde,” the first edition of which appeared in 1866. In it he takes up what he considers entirely new ground and certain of his chapters are in the highest degree interesting. His chapter on the origin of coal is perhaps more interesting than any other, and is full of suggestive reasoning. I have not seen the work cited in any of our treatises on geology, and yet the opinions of such an eminent chemist must have some weight in the treatment of problems wherein chemistry alone can furnish a satisfactory solution.