The effect of particle size of OS ash on pH and conductivity (Figure 5(a)) shows overall slight in- crease in pH and increase in conductivity to size 250 μm then decrease. Slight increase in pH and conductivity observed as a result of Oil Shale ash mass increase (Figure 5(b)); the conductivity increases faster than pH in this case. This is due to the fact that pH is a measure of [H+], whereas, the conductivity is a measure of the concentration of all ions present in the solution. Off course the more ash mass in solution the more are the ions present in solution.