Roentgen soon established that the agency responsible for the fluorescence originated at the point at which the stream of energetic electrons struck the glass wall of the tube.
Because of its unknow nature, he gave this agency the name X-ray.
He found that X-ray could manifest themselves by darkening wrapped photographics plates, discharging charged electroscopes, as well as by causing fluorescence in a number of different substances.
He also found that X-rays can penetrate considerable thicknesses of materials of low atomic number, whereas substances of high atomic number are relatively opaque.
Roentgen took the frist steps in identifying the nature of X-rays by using a system of slits to show that they travel in straight lines, and that they are uncharged, because they are not deflected by electrics or magnetic fields.