Now, in the same analogous way, we can also build a semipermeable membrane, and we can use the semipermeable membrane in a process known as dialysis. So dialysis is a process by which we can purify proteins by using a semipermeable membrane. So let's see exactly what we mean by taking a look at the following three diagrams. So, let's begin with diagram A. In diagram A, we have this beaker that contains pure water, and we also have the bag. Now, the bag is enclosed in a semipermeable membrane.