and a carbon dioxide gas the product is dispensed from dispensing orifice 12 and the gas builds pressure within the chamber once initial passage of the product seals dispensing orifice 12 once feeding of the substances is completed the gas because of backpressure created by the reaction and sealing of the dispensing orifice 12 would back flow into the feeding system and cause damage and cross contamination to such system unless otherwise prevented however check valve 14 closes due to such backflow and thus protects the feeding system from potential damage and cross contamination fig2 illustrates the end of the check valve holes 21 and 22 permit entry of substances from the feeding system not shown in this figure into the check valve where the substances pass through the check valve and exit into the chamber of the device fig3 is a cross sectional view of a check valve suitable for use in the invention the substances are admitted into opening 31 of the check valve and pass into the reaction chamber through exit opening 32 the check valve is in the closed position during operation of the device and while the check valve is in the open position and secured to the ends of the two tubes by a nut not shown two liquids are expelled from the feeding tubes not shown and are forced into the rear portion 37 of check valve 30 the liquids push valve stem 35 forward in the direction of flow check valve 30 may be held in place in the mixing and reaction chamber by crimping the back portion of the mixing and reaction chamber rather than crimping the back portion of the mixing and reaction.