The most important advantage of mercury over oil, is that a fair amount of pressure can be maintained within the inert gas system (equivalent to the height of the mercury column). Tall columns may be used to exploit this further. By increasing the pressure within the inert gas system, boiling points are increased, allowing reactions under reflux to be carried out at a higher temperature. Also, cannula transfers are accomplished more easily due to the greater gas pressure available to push a liquid reagent from a vessel, through a cannula, into another vessel.