The effect of manufacturing and packaging conditions on the stability of effervescent tablets has been studied. Mixtures of sodium bicarbonate and tartaric acid were compressed at tabletting forces of 3,6, and 9 ton force. Tablets were more than simple physical mixture but the effect of tabletting force has not been found in this force range. "Curing" the tablet by heating it to $90^{circ}C$ was effective on increasing the stability and the silica gel in the aluminium pouch stabilized the system. The equipment measuring the carbon dioxide pressure in this experiment was very useful in evaluation of the effervescent tablets.t tablets.