Engelhart’s dissertation, presented before the medical faculty at the University of Göttingen, contains the first determination of the molecular mass of a protein (hemoglobin). Engelhart proved that the ratio of iron to protein is identical in the hemoglobin of several species, and that the iron in blood could be removed by the action of chlorine. From the known atomic mass of iron he calculated the molecular mass of hemoglobin to be n x 16,000 (n being the number of iron atoms in hemoglobin, now known to be 4). Engelhart’s calculation was greeted with incredulity by his colleagues, who refused to accept that any molecule could be so large, but a century later Gilbert Adair confirmed Engelhart’s results by measuring the osmotic pressure of hemoglobin solutions.