All soaps are glycerin soaps! Glycerin is a natural byproduct of the saponification process, and is naturally contained in the oils and fats used to make soap. However, large soap manufacturers extract the glycerin from soaps and use it for the more profitable enterprise of making nitroglycerin and other products.
True transparent bars (clear glycerin soaps) have their glycerin content raised by boiling the soap base in alcohols and sugars before curing. This makes an extraordinarily low Ph and mild soap that is good for the skin, but it also dissolves easily–don’t leave these in a pool of water!