10 % NaCl or other salts (or other concentrations) water, pH 5 (or other) water, pH 9 (or other) sugar (dry or in solution) salt (dry or in solution) drierite (to absorb water vapor) - do not touch this - use a spatula or spoon KOH (to absorb CO2) - do not touch these - use a spatula or spoon dry ice (to add CO 2) - do not touch - use tongs laboratory gloves