A comparison of the corrosive action on Pentelic marble of nitrates and sulphates with the action of nitrogen oxides and sulphur dioxide

A comparison of the action on Pentelic marble of nitrates and sulphates with that of NO_x and SO₂ was achieved by passing the polluted ambient air through a filter pack before it entered the reactor chamber holding the marble grains. As a consequence the air reaching the marble was free of nitrates and sulphates, while it contained all the NO_x and SO₂. The effects on the marble grains were quantified and compared with those from a reactor through which unfiltered ambient air was passed simultaneously and under the same conditions. It was found that the action of the acids was much greater than that of the oxides, despite the fact that the concentrations of the latter were much greater.