Sentence:  In our work the best procedure for removing substances causing nonspecific staining in order to obtain specific conjugates was to pass the conjugates through a DEAE-cellulose column and in some cases to absorb the first and second milliliter fractions with sweet clover tissue <WSD>powder</WSD> . 
Meaning of the word marked with <WSD> tags:  a solid substance in the form of tiny loose particles; a solid that has been pulverized