Which one of the following statements is not correct?

Cathode rays are streams of fast-moving electrons that originate from the cathode and travel toward the anode in a discharge tube. These rays themselves are invisible to the naked eye; however, their presence is detected when they strike certain materials, such as the glass walls of the tube or phosphorescent screens, causing them to glow. Television picture tubes are a common application of these cathode-ray tubes (CRTs). Crucially, J.J. Thomson's experiments proved that cathode rays consist of negatively charged particles (electrons) that are universal constituents of all atoms. Therefore, the characteristics of cathode rays (such as their charge-to-mass ratio) are independent of the material of the electrodes or the nature of the gas present in the tube, making statement 4 incorrect. In contrast, 'canal rays' or positive ions do depend on the gas used.