Syringe used by Joseph Lister in experiments on the souring of milk, c. 1878

This glass syringe was used by Joseph Lister (1827-1912) in his experiments on the souring of milk. He discovered that milk straight from the animal is generally free from bacteria. But when examining sour milk he found that the micro-organisms present were of a type which he had previously named Bacterium lactis. The syringe could measure one or more hundredths of a minim – a minim being 0.062 ml. Such accurate measurements meant that Lister could calculate the number of bacteria in as little as one fiftieth of a minim. Lister’s work on the souring of milk is rarely mentioned as it is normally eclipsed by his work on antisepsis.