Its rarity and cost made it a controlled material where only the wealthiest of guilds or the most influential of individuals could negotiate getting some of it. The rock was nothing special by its lonesome, and alternative applications for it so far were proving to be slim pickings, but splash some water on the rock and that was when the magic happened. One could accurately measure exactly how much gas was released from the vigorous chemical reaction of water and helemnite per ounce to an absurd degree, with only the relative purity of the portion of helemnite making any degree of difference. It made measuring the pressure yields and lift necessary in airship calculations much simpler as well as being a remarkably convenient means of transporting the material before applying it, provided you waterproofed it every step of the way, of course. They had climbed on board and up through this same airlock back when they were first setting up the ship, all the while fumbling about in the deflated envelope, and emptied a canister of water on the helemnite they had acquired and quickly exited back through the sealed airlock to watch the process of expansion take place from the outside.