Sentence:  Each initially contained 1700 ml of buffer ; in the sphere was starting buffer and in the cone was final buffer , 0.50 M in both * * f and Tris , <WSD>pH</WSD> 4.1 . 
Meaning of the word marked with <WSD> tags:  (from potential of Hydrogen) the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic);