The experimental work of this investigation was done by Grace D. Bradshaw in the chemical laboratory of Cornell College. The purpose was to determine whether the silica exists in a free condition or is in the form of a silicate; also to ascertain whether the iron is in the ferrous condition as carbonate or is in the form of ferric oxide. The rocks abound in many parts of Iowa, and belong to the Niagara formation. The stratified character even in a small section is apparent, and the layers differ somewhat in composition, as shown by the varying amounts of iron visible in different portions. The rocks are used as building stone to manufacture quicklime and in MacAdam paving.