The residual animal fat and ash collected under the ceremonial altars. You'll find from reading the rest of these pages, fat, ash and water are the key ingredients of soap. When the fat and ash mixed with the rain, the mixture flowed down the slopes to the banks of the Tiber River where washerwomen were cleaning clothes. It is doubtful it really happened this way as there is a little more to the soapmaking process, but it makes for an interesting tale. There is some confusion between soap and cleansing items for shower and bath which are not really soaps at all, but detergents.
Detergents differ from soap because they contain petroleum distillates instead of fats or oils.
Glycerin which is a natural by-product of this process remains in the finished soap. This natural emollient will make your soap kind to the skin. Blender Method - to make one pound batches only. Continuous Process Method - the method by which commercial products are made. Boiling Method - Steam is introduced into the soap mixture.