Here we are boiling solvent. We are removing the solvent and when the solvent comes up here the condenser then the state of the solvent gets converted from gas to liquid and it is coming down here and we recover it in this flask. This solvent you can reuse it so you can reuse it for other experiments and an particular for example if you are carrying out some extraction in this case you will need a lot of solvent so it is more practical to reuse the solvent that you recover here but you need to be attention to wash the condenser very very well to recover only the pure solvent for example if you are working with Hixane you will have only Hixane if you are working with the chloroform you will only have chloroform it is more economic here we have rotation movement y so to keep the temperature uniform and the same temperature and all over the sample. So the liquid that we have inside the flask we will have the same temperature in every place here here here here but if we stop the rotation we might encounter some issues so it is very recommended to have rotation and more than that the advantage of rotation is to excite the solvent so when we mix the solvent we will have more excitation so the solvent will come up very quickly then to keep it like that as increasing the rotation you can increase also the area movement of the solvent