Sentence:  The samples for liquid <WSD>phase</WSD> thermal reaction studies were prepared in Pyrex capillary tubing 2.5 mm. i.d. and about 15 cm. long . 
Meaning of the word marked with <WSD> tags:  (physical chemistry) a distinct state of matter in a system; matter that is identical in chemical composition and physical state and separated from other material by the phase boundary