Barium hydroxide is soluble, which signifies that it will produce ions in the solution. Supplementing carbon dioxide will result in a precipitation reaction with Ba(OH)2, which is as follows:
Ba(OH)₂ (aq) + CO₂ (g) → BaCO₃ (s) + H₂O (l)
As the ions are withdrawn from the solution, there is a reduction in the conductivity, due to this blowing carbon dioxide gas into aqueous barium hydroxide reduce.