The cresols are also extensively used for making soaps named carbolic. These substances impart more odor to the soap and really have more disinfecting powers than phenol when incorporated with soap. Other soaps, containing the phenol group, which are well known are resorcinol soap, salol soap, thymol soap, naphthol soap, etc. From one to five per cent of the compound after which the soap is named is usually incorporated with the soap. PEROXIDE SOAP. Hydrogen peroxide in itself is an excellent disinfectant. It loses all its medicinal value, however, when added to the soap. To overcome this objection various metallic peroxides are added to the soap, as sodium peroxide, zinc peroxide and barium peroxide. These generate hydrogen peroxide by the addition of water. Sodium perborate is also used in peroxide soaps, as this substance is decomposed by water into hydrogen peroxide and sodium metaborate. MERCURY SOAPS. Mercuric chloride (corrosive sublimate) is most extensively used for the production of mercury soaps. Because of its extremely poisonous properties care should be taken in using it. Since it really eventually loses any antiseptic value in the soap through forming an insoluble mercury soap it might better be omitted entirely. LESS IMPORTANT MEDICINAL SOAPS. While the above mentioned soaps are probably the best known medicated soaps, there are numerous other soaps which may be classed under these kinds of soaps. Thus we have cold cream soap, which can be made by adding Russian Mineral Oil, 1 to 5 per cent., to the soap; witch hazel soap, made by the addition of extract of witch hazel; iodine soap, made by adding iodine or iodoform; formaldehyde soap, made by adding formaldehyde; tannin soaps, made by adding tannin. In fact, there have been incorporated in soap so great a number of substances that the list might be greatly enlarged. Medicated soaps are not only used in solid form, but in powder, paste and liquid soap as well. The only difference in a soap like those just referred to is that the medicant is incorporated with these forms of soaps as convenience directs. CASTILE SOAP. A pure castile soap should be made from olive oil. This, however, is not always the case, as a number of oils as well as tallow are used to adulterate this oil to cheapen it, and there are even some soaps called castile which contain no olive oil at all. Most of the pure castile soap used in this country is imported, as it is a difficult matter for the American manufacturer to compete with the pure imported castile soap, since both labor and oil itself are so much cheaper in the vicinities of Europe where this oil is produced, that this advantage is more than compensated by the carrying and custom charges by importing the castile soap.