Although Popper rarely examined the "life of the laboratory" (Latour's phrase), some of his epistemic doctrines reveal important themes about knowledge-acquisition in the laboratory sciences. In particular, when modern instruments are needed for exploring the subatomic realm, empirical evidence is dispositional in a Popperian sense. Evidence is defined conditionally with respect to a complex system of technological apparatus and theoretical judgments. After summarizing certain elements of Popper's epistemology Section l. The character of observation in the laboratory sciences is explored Section 2. A conception of property as capacities is then developed Section 3. This conception of property is applicable to empirical studies using modern scientific instruments, as information-processing systems.