<P> 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 a meticulous process of 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 . </P> <Table> Puerperal fever mortality rates for the First and Second Clinic at the Vienna General Hospital 1841--1846 . (Data for more years are available .) <Tr> <Td> </Td> <Td_colspan="3"> First clinic </Td> <Td> </Td> <Td_colspan="3"> Second clinic </Td> </Tr> <Tr> <Td> Year </Td> <Td> Births </Td> <Td> Deaths </Td> <Td> Rate (%) </Td> <Td> </Td> <Td> Births </Td> <Td> Deaths </Td> <Td> Rate (%) </Td> </Tr> <Tr> <Td> 1841 </Td> <Td> 3,036 </Td> <Td> 237 </Td> <Td> 7.8 </Td> <Td> </Td> <Td> 2,442 </Td> <Td> 86 </Td> <Td> 3.5 </Td> </Tr> <Tr> <Td> 1842 </Td> <Td> 3,287 </Td> <Td> 518 </Td> <Td> 15.8 </Td> <Td> </Td> <Td> 2,659 </Td> <Td> 202 </Td> <Td> 7.6 </Td> </Tr> <Tr> <Td> 1843 </Td> <Td> 3,060 </Td> <Td> 274 </Td> <Td> 9.0 </Td> <Td> </Td> <Td> 2,739 </Td> <Td> 164 </Td> <Td> 6.0 </Td> </Tr> <Tr> <Td> 1844 </Td> <Td> 3,157 </Td> <Td> 260 </Td> <Td> 8.2 </Td> <Td> </Td> <Td> 2,956 </Td> <Td> 68 </Td> <Td> 2.3 </Td> </Tr> <Tr> <Td> 1845 </Td> <Td> 3,492 </Td> <Td> 241 </Td> <Td> 6.9 </Td> <Td> </Td> <Td> 3,241 </Td> <Td> 66 </Td> <Td> 2.0 </Td> </Tr> <Tr> <Td> 1846 </Td> <Td> 4,010 </Td> <Td> 459 </Td> <Td> 11.4 </Td> <Td> </Td> <Td> 3,754 </Td> <Td> 105 </Td> <Td> 2.8 </Td> </Tr> </Table> <Tr> <Td> </Td> <Td_colspan="3"> First clinic </Td> <Td> </Td> <Td_colspan="3"> Second clinic </Td> </Tr> <Tr> <Td> Year </Td> <Td> Births </Td> <Td> Deaths </Td> <Td> Rate (%) </Td> <Td> </Td> <Td> Births </Td> <Td> Deaths </Td> <Td> Rate (%) </Td> </Tr>

When did health care workers first use chlorine solution to decontaminate their hands