A run was set up with one tube capped and the other left open. At the start point the ambient humidity was about 62%. As ambient temperature increases the internal humidity of the closed container decreases according to Charles’s Law and vice versa as the room temperature decreases. The ambient humidity also shows the expected temperature dependence but, because the system is open, water vapour can enter or leave the room and this of course disrupts the strict relationship of the observed humidity with temperature.

In this second run,  Solpadiene tablets or Solpadiene capsules were added to the tubes and capped. Immediately the internal humidity drops as the products absorb water vapour from the air inside the HDPE containers. This occurs independent of the humidity - temperature relationship as the products change the vapour pressure of the water vapour due to it being absorbed. This continues until the Equilibrium Relative Humidity of the products is reached, which in this case is about 48%.