In 1884 he developed a type of filtration known today as the Chamberland filter or Chamberland-Pasteur filter, a device that made use of an unglazed porcelain bar. The filter had pores that were smaller than bacteria, thus making it possible to pass a solution containing bacteria through the filter, and having the bacteria completely removed from the solution. He was also credited for starting a research project that led to the invention of the autoclave device in 1879.
He worked with Pasteur and came up, by chance, with a vaccine for chicken cholera. He went away on holiday, forgetting to inject the disease into some chickens as he had been told. When he came back he saw the jar of bacteria sitting on the side and thought he would inject it into the chickens anyway. To his amazement they did not die. He reported this to Pasteur, who told him to inject a fresh form into the chickens. He went on to injecting the fresh form into same chickens, and they didn't die. He had found a vaccine! They had also discovered that a weakened form of a disease can act as a vaccine.