A study is made of liquid films ejected from the rims of rotating disks with liquid supplied at the centre. The variation in film area with alteration in experimental conditions is best explained by the assumption of a limiting film thickness, the "breaking thickness," for each liquid, below which the film can no longer exist unsupported in the air in the face of disruptive forces. This assumption is supported by experimental evidence including a study of the paths of liquid particles and liquid films before and after leaving the rotating disk, and a rough measurement of film thickness. A distinction is made between films tending to ellipsoidal shape whose peripheral thicknesses vary within fairly wide limits, and substantially horizontal films whose dimensions are governed by the "breaking thickness" of the liquid concerned. The mechanism of the formation and destruction of these liquid films is discussed and differences in the behaviour of water and glycol examined.