Abstract: A method of treating substances in an ambient environment with a cryogenic material is disclosed comprising a barrel having a plunger mechanism movably mounted therein and having a valve on the lower end thereof. The valve normally closes the lower end of the barrel but the plunger may be moved relative to the barrel to permit cryogenic liquid such as liquid nitrogen to by-pass the valve and to move upwardly into the interior of the barrel. The valve has a tip portion at the lower end thereof. The barrel is removably positioned in a guard so that the tip portion extends outwardly through the bottom of the guard and so that the upper end of the plunger is exposed above the guard. The tip portion has a lower end portion which is extremely thin so that the cryogenic liquid will be positioned closely adjacent the skin but not in actual contact therewith when the tip portion is placed into contact with the patient's skin. The method of charging the device is disclosed as is the method of using the same.