Aetheric Elements
Beginning in 1829, Johann Wolfgang Döbereiner started plotting out trends in the properties of elements. He noted that some elements had similar properties with other elements in groups of three. English chemist John Alexander Reina Newlands saw a repetitive pattern and in 1869 published his law of octaves which states that "any given element will exhibit analogues behaviour to the eighth element following it in the table." Dmitri Mendeleev published his periodic table in the same year and his presentation became the standard seen in classrooms throughout the world.
There were gaps, though. The most obvious was across the top where hydrogen seemed to sit by itself. The test of a good scientific theory is in it's predictive properties. Mendeleev's predictions were borne out with the discoveries of Gallium (eka-aluminium) in 1875, Scandium (eka-boron) in 1879, and Germanium (eka-silicon) in 1886. Additionally, without knowing why the elements sorted out the way that they did, there was no reason to exclude the possibility that not only were there undiscovered elements between hydrogen and helium but there may also have been elements of a lesser atomic weight than hydrogen. Mendeleev speculated that a lighter member of group 0 (the noble gases) might have been responsible for radioactivity. Both he and Lord Kelvin described the aether in terms of being very light, rarefied sub-hydrogen elements.But that space along the top, the half a dozen elements between helium and hydrogen and anything lighter, never turned up and the early 20th Century discoveries of the internal structure of the atom made it clear that such things would never be discovered. This, however, didn't stop people like Walter Russell from insisting into the mid-20th Century that not only were there elements to be found there but that there were some 24 elements down below hydrogen and these were all tied together in a unified theory of light and mind.
". . . I always looked for the Cause behind things and didn't fritter away my time analyzing Effect. All knowledge exists as Cause. It is simple. It is limited to Light of Mind and the electric wave of motion which records God's thinking in matter."
Russell's disregard for evidence allowed him to create a thorough, unified cosmology without the hindrance of having any basis in reality which was, therefore, utterly convincing to the ignorant.
You could write your story with helium but, if I can nit pick, there are some problems with that. Firstly, helium didn't become more widely available until after the turn of the century when the element turned up in natural gas wells of Kansas and the panhandles of Texas and Oklahoma. And America kept a monopoly on the gas, refusing to seel it to Germany, the world's leader in commercial airships. You could simply change history to have helium deposits discovered earlier. Since you are probably also pushing back the innovations in aluminum processing that allowed for lightweight zeppelin superstructures, pushing back helium deposits isn't going to be an added narrative burden.
Secondly, helium has a lifting capacity of about 8% less than hydrogen. If you are going to change history, you might as well change it for the better. At least in so far as it allows your airship pirates to carry more booty in the ship's hold.Enter sub-hydrogen elements.
Make the sub-hydrogen element a noble gas and you don't have to worry about it being flammable. Being lighter than hydrogen, it will have more lifting power. No more than about 7% more than hydrogen (as I discussed in my review of "The Secrets of Delleschau") but still an improvement. Wallace called these sub-hydrogen noble gases alphanon, betanon and gammanon. Remember, however, that Mendeleev thought that perhaps radiation originated from these gases. The price one might need to pay.(Take a few minutes to read the alphanon link and some of the "see also" links at the bottom of that page. Great guns, the woo density is astonishing. "The compound interetheric or seventh subdivision actuates sympathetic polarization to produce action and sympathetic depolarization to neutralize it, in the body as well as in matter." Wow.)
If one is going to fill an airship envelope with a sub-hydrogen element for lift, the next question is to where all that gas is going to come from. I had mentioned helium before. Scientists had deduced the existence of helium in 1868 through spectrographic analysis of the sun and in the 1880s and 90s it was detected in lava and radioactive rocks here on Earth but it wasn't until 1903 that significant amounts of helium were discovered in a gas well in Kansas. In an alternative history, pockets of sub-hydrogen elements could be discovered in the same way.If we are talking about the aether specifically; the rarefied gas through which light propagates, then it is already all around us. One would need to come up with a way to distill, compress, condense or liberate the aether.
One person who claimed to have done just that was James Worrell Keely. The "hydro-pneumatic pulsating vacuo-engine" he built in 1874 used a tuning fork and rotating copper spheres to disintegrate water, releasing the aetheric gas within and using the enormous pressure to drive a motor. I'll be going into more detail concerning Keely in a future posting but suffice it to say that he committed fraud on a grand scale.Something else to consider in a steampunk physics is what would happen if you were to distill the aether out of the space around you. Without the aether there would be no medium through which heat and light could propagate. Turning on an aether machine might make a very cold and dark space space around the machine.
The plots almost write themselves.