Except for the matter of brittleness unglazed clay is a most excellent pipe stem. Clay is usually cool and very absorbent of the acrid oils occurring in the distillation of tobacco. When the end of a clay stem is protected by a rubber band, it forms a very good mouthpiece. Bone and other materials are also used as mouthpieces. Ebonite is used, but is objectionable because it spoils the flavor of the tobacco. Celluloid is a dangerous substance and should not be used as a pipe stem. The smoker should avoid biting the mouthpiece as it roughens it. It is far better to discard a mouthpiece when it becomes indented, rough or worn in any way. A damaged mouthpiece should on no account be used when the lips are chapped or lacerated because the irritation may, if continued, lead to ulceration and tobacco juice is not beneficial to skin lesions. SPECIAL PIPES German pipes are, as might be expected, the most correct in scientific principle. The pipe has two bowls the upper of which is for the tobacco. This fits into a socket which allows the oils and aqueous solutions due to the distillation to pass into the lower bowl, very little getting into the stem. The bowls are usually of porcelain and the long curved stem is of wood mostly cherry. The Dutch pipe is similar to the German except that the stem is long and straight which allows the bowl to rest on the ground. The German pipe is usually held in the hand by the lower bowl. In Turkey and Oriental countries the water pipe is used. This form of pipe originated in Persia. The pipe consists of a receptacle for the tobacco, which has a perforated bottom. This holder fits into a cup from which a hollow tube leads into a jar containing water. The tube passes through the stopper of the jar and descends almost to the bottom of the water. Another tube, the inhaling tube, also passes through the stopper of the jar, but does not reach to the surface of the water. On drawing through the inhaler a vacuum is created in the air space above the surface of the water in the jar which induces suction through the other tube below the water level. The smoke therefore bubbles through the water and is cooled before it reaches the mouth of the smoker. It, however, requires a considerable amount of effort to draw the smoke through. Water pipes are used extensively among the better classes of the East. Some of them are very gorgeous affairs, the bowls being of the richest crystal and the fittings gold or silver set with gems. Sometimes they have several smoking tubes so as to accommodate more than one smoker. The water pipe used by the Shah of Persia is said to be worth $400,000.00. In Turkey the water pipe is known by the name of Hookak. In Egypt it is called Nargeeleh (or Narghile) because the water vessel is usually a cocoa nut for which the Arabic name is Na'rghee'leh. The Hookak usually stands on the floor and is ponderous, with many smoking tubes. The Nargeeleh is a hand pipe.