I haven't been able to let go of the notion that there is a special long-lived allotrope of hydrogen of mass-5.
For now, this putative species is being labeled as H5. Presumably it would consist of two molecules of normal hydrogen (H2) magnetically or hydrogen-bound to one reduced Bohr orbital atom of hydrogen (aka the hydrino). This hydrino would have a very large magnetic self-field and that field (with or without anything else) might be enough to provide long-lived stability in a liquid phase for the allotrope. If this putative allotrope were stable, it would most likely be liquid at a low-mid temperatures, but much higher than expected; and it should show up in cosmology in cold gas-giants like Jupiter. It could be a liquid at up to 200K. It might show up as a liquid in the polar regions of Mars. Unfortunately the spectrum of this liquid allotrope, if it exists and is marginally different from gaseous H2, is unknown (or at least unpublished), and we have no samples of gas from the gas giants anyway, yet there are some tantalizing clues there. Some of what is said to be "lakes of liquid methane" on the Jovian moons seem to contain way too much hydrogen. I had been wondering about comet tails as well. We can easily test the spectrum lines of comet tails, and possibly even collect gas from them. When you think about it, even though the solar system is composed of 90% or more hydrogen, comets "should" contain little hydrogen except as chemical compounds like methane or ammonia - almost zero... This is because they are not cold enough to hold H2 as a liquid, and they are of low mass anyway - so the bulk of any H2 which might have been collected out in the Oort cloud, as they orbit through it, simply would not "stick" for very long unless it were itself liquid. None of the gaseous H2 which is encountered could ever be expected to condense down to the extremely low temperature where hydrogen becomes a liquid (space is cold but not that cold) - and therefore any hydrogen found in comet tails would need to be bound as hydrides or chemicals, which can happen, but not in large amounts. Yet, it is known that some comets are surrounded by huge "halos" of gaseous H2 (clouds bigger than the Sun in diameter) long after they have left the Oort cloud - and then they begin to lose this halo as they further heat up in the solar system. IOW most of their mass is lost in a delayed fashion, indicating that it must have been liquified and is boiling-off ... but the bigger issue is how it got there semi-permanently to begin with; and how it stayed bound to the comet for many years before boiling off. There is way too little gravity. Could this gaseous H2 have been available in the form of a liquid allotrope, with a rather high boiling point (~200K) in the Oort cloud ? Could a comet pick up lots of this putative H5 on every pass? It would need to be a fairly predictable amount every time, since most comets are on a regular (but imprecise) orbital schedule. Jones
