That old-fashioned camera (that is, piles of white powder will flash when pressed). What's that white powder?

That thing is called magnesium light, which is the earliest flash. It uses current pulse to ignite magnesium powder, and the strong light generated by combustion is used as the light source. Later, it gradually evolved into a bulb flash. I may have seen it in a movie. There is something like a hemispherical lampshade on the camera. The concave ball faces forward, and a high-power flash bulb is installed inside. Such flash bulbs were disposable at that time, and a light bulb was changed every time a photo was taken. So photographers at that time would have pockets full of light bulbs, which were not much smaller than what we use now. Think about how bad it would be if you fell: o)