Sentence:  Some 80 <WSD>reaction</WSD> tubes from 13 manifold fillings were illuminated in the temperature range from 40 to 85 ` in a further endeavor to determine the cause of the irreproducibility and to obtain information on the activation energy and the effect of light intensity . 
Meaning of the word marked with <WSD> tags:  (chemistry) a process in which one or more substances are changed into others