In the trucking section of South Philadelphia the air is often heavily loaded with combustion products from great industrial plants, railroad engines, and other sources. The soils of this region, consisting of Sassafras loam, are somewhat acid but not more so than another area of the same soil type at Monmouth Junction, New Jersey, where there is little smoke. Other sandy soils, of DeKalb areas, have shown approximately the same PH values. The geographical distribution of acidity in South Philadelphia apparently is not correlated with the location of the smoke producing plants. With better cultural methods, cultivated lands in another type of soil have been kept near neutrality