.......and it can be supplied in metal cylinders.....
And if you bubble the gas thru water, you get hydrochloric acid.....
#HCl(g) + H_2O(l) rarrH_3O^+ + Cl^-#
.....equivalently......
#HCl(aq) rarr H^+ + Cl^-#
The point is that #HCl(g)# is mighty soluble in water, to the tune of approx. #10.6*mol*L^-1# - this is conc. hydrochloric acid......this is the reagent they supply in bottles......
The hydronium ion, #H_3O^+#, is a conception not an actuality. As far as anyone knows, the actual species is a cluster of 3-4 water molecules with an EXTRA proton, i.e. #H_7O_3^+#, or #H_9O_4^+# - this is what we mean when we write #HCl(aq)#.......we write, without loss of generality, #H_3O^+# or even as #H^+#.
I have said much the same thing here.