The effect of particle size of Oil Shale ash on pH and conductivity (Figure 5(a)) shows overall slight increase 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.