A visit to Bridge of Orchy on March 8th brought (in the first instance) disappointment, and then delight. The weather forecasts were heavy with snow and challenging winter conditions; the reality was a pale and parched landscape with a mere garnish of snow on the top 100m.
I’d hoped for much more in the way of spectacle, but it was very cold and had been for a while – if you can’t have snow, there can be ice in crafty places.
The West Highland Way, our route for a short walk down to Tyndrum and the mid-afternoon train home, is crossed by many a burn, usually culverted under the track. There are miniature cataracts above the path, and falls below, and after a long cold spell, there is magic. Ice is just a nuisance in the city; unless you can stay on gritted streets, you can skate about perilously for a good while until a thaw sets in. But in a wilder place where there is falling water and a long cold, ice is fleeting sculpture and captured starlight. The sun gets to it quickly and it is gone, but sometimes the thaw is more beautiful still than the solidity.
I thought of writing this because John, my father-in-law, showed me a nice photograph of my brother-in-law Ian, then a schoolboy, sporting one of those enormous crystals of copper sulphate pentahydrate which can be grown by suspension. I used to grow crystals – it was one of the best things about working in the laboratory. Organic chemists often need a hard proof of the way the atoms are connected in the molecules they’ve made, and much can be had from a good crystal structure. Crystallographers like a small, clear and regular crystal (“a cube or rhombus or prism or…, about 0.5 mm of side, please, if it’s bigger, I’ll have to cut it…”) to mount in their X-ray diffractometers – needles are less popular, flaws and defects even less so. There are special methods for growing small but very regular crystals to keep your crystallographer happy. It is hard to imagine anything less useful than an icicle for three-dimensional structure solution, particularly when they have ribs from freeze/thaw events.
But what a sight they are when the meltwater filming their surfaces, and their internal flaws, catch and scatter the sunlight. The ice features found in the wild testify to changing temperatures. Wild ice is often templated by vegetation – even a single strand of grass will sustain an epic of freeze and thaw. Bigger leaves make for impressive structures.
Bulk crystallisation is maybe the best way of purifying something you’ve made – and it is of enormous importance to the big economy. Pharma companies need to purify metric tonnes of gear as they bring their compounds to the pharmacy. The process is broadly the same if you’re doing the odd gramme in the lab or 100 Kg in a big stirred tank in a factory, and I know a lot more about the former process. At the end of your reaction and the pre-purification (probably some column chromatography), you might be left with an oil or syrup, and you’d be thinking that there might be a crystalline solid in there somewhere. So you’d find out what your stuff dissolved in (the solvent), and what it didn’t (the precipitant). You’d try “scratching it” which meant literally scratching the inside of the flask which contained your stuff with a glass rod (carefully), the idea being that microparticles of glass detach and nucleate the crystallisation of your compound. If you couldn’t get a result doing this, you’d dissolve your stuff in hot solvent and then let the solution cool down slowly – I’d wrap my flasks in cotton wool to try and slow the cooling. Whichever method you used, there would be a a moment when some clear stuff in a flask would start to flash and glitter as crystals emerged, and then you’d have a slush of beautiful crystals and you’d plunge the lot in an ice bath to get the extra few percent on your yield, usually a moment of triumph. If all of that failed, there were mixed solvent methods to be tried when you would use the precipitant to control solubility. The really good bit was the emergence from solution into solid phase – ice usually forms too slowly for anyone to see it but in the flask, there are extraordinary seconds when you feel you are witnessing all the forces that order the universe. These images remind me of those moments. I can’t easily walk away from wild ice when I have the camera to hand and there is some good daylight. I hope you enjoy this selection almost as much as I enjoyed recording the images. They were all taken in the West Highlands in the months of January, February and March with a hand-held camera, apart from the very last image which was recorded from a tripod with a very slow shutter.
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