Complex sentence: To make sure that the ratio of the cations to anions is accurate, the solution must be slowly added from one to the other and the one that is added to must be constantly stirred while and after the two solutions are mixed.
Split into simpler sentences: To make sure that the ratio of the cations to anions is accurate. The solution must be slowly added from one to the other and the one that is added to must be kept stirring while and after the two solutions are mixed.