Project GRFT's 2nd Gene Gun

 David checks the 2nd gene gun that he built for leaks prior to it's departure from CCL to Hector's lab.  If there is any leakage in the tubing or valves, helium, being of low density, will escape.  It is this low density of He, combined with its properties of  being non-reactive, non-toxic, inert and diffusible that make it a good choice as a propellent.  

The first gene gun made used gunpowder as a propellent.  This was crude and dirty compared to today's helium powered gene guns.   Good work, David and Hector.