(1). Freshly precipitated silver bromide has a large surface development and is subject to thermal aging at room temperature in the air-dried state. During the aging the magnitude of the surface decreases and also the speed of incorporation of radioactive bromide, when bromine dissolved in ethyl bromide or in a gas phase is shaken with the solid. (2). A rapid exchange occurs between bromide in fresh air-dried silver bromide and radioactive bromine dissolved in ethyl bromide or bromine in the gas phase. (3). Fresh silver bromide has a relatively large electrical conductivity which is at least partly ionic.