Sentence:  For the albumin method , equal <WSD>volumes</WSD> of 30 % bovine albumin , sample and 2 % cells suspended in saline were allowed to stand at room temperature for 1 hr and then were centrifuged at 1000 rpm for 1 min . 
Meaning of the word marked with <WSD> tags:  the amount of 3-dimensional space occupied by an object