Page:An outline of English phonetics ... with 131 illustrations (IA cu31924027389505).pdf/26

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exactly, and it must be so made that it will keep in position by itself; it should be provided with little projecting pieces in the front so as to admit of its being removed from the mouth easily (A A fig. 3). If the material is not black the under side should be blackened with varnish.

*40. An artificial palate sufficiently good for ordinary purposes may be made as follows. Soften some dentists’ wax by putting it in water, warmed to a temperature of about 60° C. (= 140° Fahr.). Spread it on a dentists mouth-tray and introduce the tray into the mouth; then press it upwards so that the soft wax becomes moulded into the shape of the palate. Remove from the mouth, and allow the wax to cool. When quite hard, oil the surface of the model thus obtained. Then cover the surface carefully with a piece of damp filter paper, taking care that no air-bubbles are left between it and the wax. On the op of this place a thin layer of seecotine or other strong gum well mixed with precipitated chalk. Apply a second piece of damp filter paper taking care as before not to leave any air-bubbles. When the whole is thoroughly dry, the paper may be removed from the wax and cut out along the line marking the edge of the teeth. The under side of the artificial palate thus obtained should be covered with black varnish.

*41. The artificial palate is used as follows. The under side of the palate is first covered with a little finely powdered chalk and inserted into the mouth. A sound is then pronounced and the palate is