A device for testing soil samples is comprised of a closed container having an interior compartment with upper and lower portions. A valve is provided for introducing into the closed container a liquid having the general properties of butane, and a second valve is provided in the container for allowing gas in the closed container to exit therefrom. A soil sample filter container is suspended within the container above the bottom portion thereof. A condensation element is mounted in the closed container and positioned above the filter container to cause gas evaporating from the liquid in the container to liquefy as condensate on the condensation element, whereupon the condensate drips into the filter container and leaches through a soil sample therein, and then collects as a liquid in the bottom portion of the closed container. This permits a hydrocarbon residue to be left in the bottom portion of the container after the outlet valve has been opened to permit the liquid to evaporate.