Filling a vacuum in the low-pressure lubricant market
Do you believe in ghosts? No doubt you scoff at the suggestion. But as I grow older, I sometimes wonder… Let me explain. I am standing in the lab in front of the twin manifolds with which I will re-enact the pump-fill protocol that Wilhelm Schlenk developed in the 1920s. After flicking on the pump, giving thanks to Wolfgang Gaede, I raise James Dewar’s flask around the trap and pour in a litre of so of liquid nitrogen, mentally tipping my hat at William Hampson and Karl Linde. With my left hand I reach up, familiarly opening James Young’s teflon valve. With my right hand I flick on the Pirani vacuum gauge – the needle swings. The vacuum is good, but not great. Leaning in slightly I work the double-oblique stopcocks back and forth, paying homage to Clemens Winkler and Fritz Friederichs.
To my immense irritation, however, the vacuum isn’t great and working one tap it gets a bit worse. I peer grumpily at the stopcock; sure enough a line of streaks mars the clarity of the barrel. It’s time to clean and regrease the tap.