Sentence:  Faraday succeeded in <WSD>liquefying</WSD> a certain number of gases by compression and refrigeration, but there still remained a number that proved absolutely refractory to the most powerful agencies; hence these gases were called "permanent". ... A retired manufacturer, who at the same time is a distinguished man of science, M. Cailletet, has subdued the permanent gases, having succeeded in <WSD>liquefying</WSD> and solidifying them. 
Meaning of the word marked with <WSD> tags:  To make into a (liquid).