# Why does q/m ratio(specific charge) depend on nature of gas in anode ray experiment?

I can't understand why $q/m$ ratio changes in anode ray experiment (discharge tube experiment) (which was carried out by Goldstein) with change in nature of gas?

Since $q=1.6\times10^{-19}\ \mathrm C$ and $m=1.6726219\times10^{-27}\ \mathrm{kg}$, shouldn't the ratio be constant?

• Because different ions can have different charge states, and different nuclei have different masses. So, q/m is different for H+, He+, and He++... – Jon Custer Nov 14 '16 at 18:18
• I really don't see how you got that from the comment. A hydrogen atom without the electron (thus H+) is a proton. To be more specific, a protium atom without an electron is a proton. A deuterium atom without the electron is D+. But, since you specified a gas, one would go with hydrogen, or H+, since protons don't generally form an independent gas. – Jon Custer Nov 27 '16 at 22:27