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His experiments were almost entirely confined to " airs " , and out of this work emerged his most important scientific texts : the six volumes of " Experiments and Observations on Different Kinds of Air " ( 1774 – 86 ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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