To make up a solution first dissolve the solid material completely in less water than required to fill the flask to the mark After the solid is completely dissolved very carefully fill the flask to the 500 mL mark Move your eye to the level of the mark on the neck of the flask and line it up so that the circle around the neck looks like a line not an ellipse Then add distilled water a drop at a time until the bottom of the meniscus lines up exactly with the mark on the neck of the flask Take care that no drops of liquid are in the neck of the flask above the mark After the final dilution remember to mix your solution thoroughly by inverting the flask and shaking f Analytical Balance