Chemistry and materials

The seventh entry is o catalisador, in o catalisador acelera sem se consumir, and the word is Greek all the way down. Behind it stand katá, down or through, and lýein, to loosen or untie, so that a catalyst is a loosening-down. That second root is one an English reader already owns half a dozen times over without noticing. It is the lysis of « analysis », where a question is untied into its parts; of « paralysis », where the limbs come loose; of « dialysis », where the blood is loosened apart; and of « electrolysis ». The chemical sense was built on the model of « analysis » by a Swedish chemist in the eighteen-thirties, and Portuguese took the word over whole. Where the two languages part company is in the garage. O catalisador names the substance in the flask and also the box welded into a car’s exhaust; English keeps « catalyst » for the first and needs « catalytic converter » for the second, clipped to « cat » in the trade. So mudar o catalisador is a repair bill and never a laboratory note.