Sentence:  For the albumin method , equal volumes of 30 % bovine albumin , sample and 2 % cells suspended in saline were allowed to stand at room temperature for 1 <WSD>hr</WSD> and then were centrifuged at 1000 rpm for 1 min . 
Meaning of the word marked with <WSD> tags:  a period of time equal to 1/24th of a day