Millikan's Oil Drop experiment served as an argument for the atomistic theory of electricity. However historians of science have raised questions concerning Millikan's methods and his results. In my ongoing project I am analyzing material and procedural aspects of this experiment with the replication method. In doing so I first analyzed published and unpublished sources as well as material remains related to this experiment. First results of my analysis, such as the genealogy of oil drop apparatus reflecting the development of the experiment and some technical and material aspects, were lately published in the Bulletin of the Scientific Instrument Society. Recently we reconstructed an oil drop apparatus that is as close as possible to the one Millikan used in 1913. After some research concerning the peripheral devices we are now able to analyze the practice with our oil drop apparatus. In my talk I will present more technical and material aspects of the apparatus and the experiment that became evident in the process of the reconstruction. Moreover I will report on my experiences with the apparatus and relate them to Millikan’s accounts. In doing so I will add some details toward the understanding of experimental practices in the Ryerson Laboratory in Chicago before World War I.