Sentence:  He thanked me with a smiling nod, measured out a few <WSD>minims</WSD> of the red tincture and added one of the powders. 
Meaning of the word marked with <WSD> tags:  A unit of volume, in the Imperial and U.S. customary systems, 1/60 fluid drachm. Approximately equal to 1 drop, 62 μL or 0.9 grain (weight) of water.