"This result is due to a phenomenon of interference which occurs within the sensitive layer"

Gabriel Lippmann's quote is referring to the phenomenon of interference, which is a phenomenon that happens when two or more waves connect with each other. This disturbance can trigger the waves to either cancel each other out or strengthen each other, depending on the stage of the waves. In this case, the interference is taking place within the sensitive layer, which is most likely referring to a layer of material that is sensitive to the waves. This interference is causing the result that is being talked about, which could be anything from a change in the product's homes to a modification in the behavior of the waves. Interference is an important principle in physics and is utilized to explain many phenomena, such as the colors of a rainbow or the patterns of light and dark bands seen in a diffraction grating.