C’est quoi le mot pour ‘reverse osmosis?’

This morning, I had a French conversation class. The advantage of being in the first class of the day was that nobody else showed up. As such, I learned a lot of vocabulary relating to Welsh mountain climbing, desalination, battery and fuel cell technology, and fossil fuels. There will be two one-hour classes a week, focusing on conversation. It will be good to finally get back into the practice of speaking la belle langue.