Here's the verse Tom Lenehan omits. As a chemist by background, I like it! Despite Tom Munnelly's comment, I think you can make line 6 scan.
Let philosophers dabble in science and babble
'Bout Oxy-gin, Hydro-gin, Nitro-gin's fame
For their gin, to my thinking, is not worth the drinking
Their labour's all lost and their learning a drame
They may prate by the score of their elements four
That all things earth, fire, air and water must be
For their rules I don't care, for in Ireland I'll swear
By St. Pat there's a fifth and that's whiskey, machree!