The test results are shown in figure 3. It can be seen that water flooding caused a small compression of the sample (0,3% of the initial height) while flooding followed by percolation with acid and basic fluids caused collapses of 6,0 and 3,9% respectively. This indicates a clear reactivity of soil structure to the basic and acid fluids. The percolations were stopped after 24 hours, and during this period compressions of the order of l2% of the total were observed, for both fluids. It is possible that with longer periods of percolation the compressions would be even greater. Despite the fact that only one series of tests was performed, it can be inferred that the observed collapses during the tests indicate that field infiltration of acid or basic fluids might lead to significant settlements of structures founded on footings such as those of the industry buildings.