Recently, via Derek Lowe's In The Pipeline, I came across the book Ignition!, by John D. Clark. It's the story of the development of liquid rocket fuels, told by a man who was head of one of the programs. Even if you don't know much chemistry — I don't — the book makes a fascinating read. The image on the left is the first page you see when you open the book, and the image below is the second.

The images are of a rocket test going right, and of what's left after one goes wrong.

The author, John D. Clark, actually published a few science fiction stories back in the Golden Age, and the book bears an introduction written by Isaac Asimov, who was trained as a chemist. The writing is engaging and full of colourful anecdotes; I suspect that they didn't need much embellishment. After all, they tried all sorts of improbable and alarming combinations in an effort to come up with a satisfactory fuel/oxidizer combination. One memorable example was an attempt to work with butyl mercaptan — essence of skunk — as a fuel. After a test firing of those, well, apparently you could still smell them around the test stand ten years later.

The book isn't just a collection of colourful anecdotes; there's real chemistry in there. Much of the detail was beyond me, but one particular example was about a technique I remember from my chemistry classes.

The idea was to use red fuming nitric acid as an oxidizer. To be usable aboard ship, say, they needed to come up with a quick assay that would tell them how much water there was in the acid. Clark came up with one based on electrical conductivity that was nice and easy to apply. The problem was how to calibrate it: there wasn't any really satisfactory way to measure the water content even in a fully-equipped laboratory. So he went with the brute-force approach: measure the amount of acid in the mixture and subtract it from the total amount to get the amount of water. To do this he just used titration, something I actually did (though thankfully not with red fuming nitric acid) back when I was taking chemistry. But this was not a simple titration: the water concentrations of interest were only a few percent. So to measure those to within a few percent, he needed to measure the amount of acid to one part in ten thousand. That kind of accuracy takes heroic effort: when he mixed up a drum of sodium hydroxide to titrate against, he learned (by painful experience) that he had to leave it on the magnetic stirrer for an hour or else the concentration was too variable from place to place in the drum. But they ultimately managed to develop calibration curves for the conductivity meter. It's a reminder, though: that phone book sized CRC handbook sitting around every lab consists of thousands of pages of tables, each one of which was compiled by dint of such heroic effort.

Anyway, the book is great fun to read. The catch is getting your hands on a copy. It's long out of print, and when used copies are available they go for hundreds of dollars. It's not too hard to find a digital copy on any of the usual wretched hives of scum and villainy, but if you want a legal and/or physical copy I think your best bet is a good library (or a bad one that will do interlibrary loan).

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