Abstract: This invention provides an understanding of the structure and porosity of soil and stony regions. The method is characterized by release of a measuring gas in the region being investigated and its penetration through the investigated region to several places where it is captured and measured. Thus, the measured data from the various measuring locations provides the structure and the porosity of the region being investigated. The method is especially suited for the investigation of dams and the location of underground cavities and tectonic faults.

Abstract: Apparatus is provided for automatically dispensing CO.sub.2 snow on articles moved by a conveyer underneath a snow storage container-dispenser outlet opening. The dispensing is controlled by a motor driven segmented drum with brush-like elastic blades closing the dispenser outlet opening actuated when an article is moved into place thereunder. The snow is generated from liquid CO.sub.2 flowing through cooling coils in the snow and dispensed through a nozzle in the upper portion of the container in response to capacity sensing means such as a photocell level detector to thereby keep the container snow level constant.