The analysis in this Demonstration is based upon separating the different cations into groups, following selective precipitations due to the common ion effect, which, in turn, is pH related. Each precipitate must be washed at each separation, according to the standard procedures of analytical chemistry. Our choice is to represent the solution path through the vertical flow line, while the precipitates are represented by horizontal flow arrows. The bifurcations show the division of the solution into different portions. A missing cation does not guarantee the absence of precipitate because of several possible problems (e.g. incomplete precipitation). To highlight this, the precipitate that should not be there but could show up is written in red.