these destructive unknown endemic influences?" Analysis of childbed fever mortality Semmelweis was severely troubled that his First Clinic had a much higher mortality rate due to puerperal fever than the Second Clinic. It "made me so miserable that life seemed worthless". The two clinics used almost the same techniques, and Semmelweis started eliminating all possible differences, including even religious practices. The only major difference was the individuals who worked there. The First Clinic was the teaching service for medical students, while the Second Clinic had been selected in 1841 for the instruction of midwives only. He excluded "overcrowding" as a cause since the Second Clinic was always more crowded and yet the mortality was lower. He eliminated climate as a cause because the climate was the same. Theory of cadaverous poisoning Semmelweis' breakthrough occurred in 1847, following the death of his good friend Jakob Kolletschka, who had been accidentally poked with a student's scalpel while performing a post mortem examination. Kolletschka's autopsy showed a pathology similar to that of the women who were dying from puerperal fever. Semmelweis immediately proposed a connection between cadaveric contamination and puerperal fever. He proposed that he and the medical students carried "cadaverous particles" on their hands from the autopsy room to the patients they examined in the First Obstetrical Clinic. This explained why the student midwives in the Second Clinic, who were not engaged in autopsies and had no contact with corpses, saw a much lower mortality rate. The germ theory of disease had not yet been accepted in Vienna. Thus, Semmelweis concluded some unknown "cadaverous material" caused childbed fever. He instituted a policy of using a solution of chlorinated lime (calcium hypochlorite) for washing hands between autopsy work and the examination of patients. He did this because he found that this chlorinated solution worked best to remove the putrid smell of infected autopsy tissue, and thus perhaps destroyed the causal "poisonous" or contaminating "cadaveric" agent hypothetically being transmitted by this material. The result was the mortality rate in the First Clinic declined 90% and was then comparable to that in the Second Clinic. The mortality rate in April 1847 was 18.3%. After hand washing was instituted in mid-May, the rates in June were 2.2%, July 1.2%, August 1.9%, and, for the first time since the introduction of anatomical orientation, the death rate was zero in two months in the year following this discovery.