Capital Vol. 1 Chapter 10 is about the working day
Employers in Marx's time know well that "snatching minutes" from workers, e.g. 5 minutes less for lunch, means more surplus value therefore more profit
Workers are divided into "full-timers" and "half-timers" and beyond that have no individuality. They are just a source of minutes to be stolen. The capitalist profits by exploiting your time