Sentence:  Sets of reaction tubes containing 0.2 of an atmosphere of added oxygen in one case and added moisture in another , both gave reaction rates in the <WSD>range</WSD> of 0.1 to 0.4 of the chlorine exchanged per hour . 
Meaning of the word marked with <WSD> tags:  an area in which something acts or operates or has power or control: "the range of a supersonic jet"