If there are openings in the parts of the face, such as the nostrils or the auricular orifice, they should be plugged lightly with dry absorbent cotton, care being taken, however, to avoid distending the alæ. The plaster is now prepared in a small porcelain or soft rubber bowl by adding warm water to it until the powder, upon stirring, forms an even semiliquid paste. This is poured first upon the area to be reproduced to fill all the finer crevices and to avoid air holes, and is then put on with a spatula, or wooden slab, until the space within the clay boundary is properly filled, covering the organ all over with a layer ¼ to ½ inch in thickness on all sides. Over the eyelids a thin coating of plaster should be used, whereas over other parts of the face a thickness of half an inch can be allowed without discomfort to the patient. It is well at first to make the plaster thick, as the mold is liable to be broken upon removal or in drying. After a little experience splendid results are obtained with very thin walls of plaster. The plaster is allowed to dry and harden, while the patient is instructed to remain still and silent. If a cast of the nose is made, the patient should refrain from talking and breathe gently through the mouth. Tapping on the plaster now and then with a lead pencil will show when it has hardened sufficiently to be removed. A firm, quick pull relieves the mold. In molds of the ear an anterior and posterior impression should be made, if a cast of the entire organ is desired. This can be done by first applying a layer of plaster to the posterior surface up to the outer rim, allowing this to harden and painting the anterior ear and the exposed plaster border with petrolatum before putting the plaster over it. Upon traction, when set, the plaster will separate readily at the point of the separation. The removed piece of set plaster is called the mold. It is allowed to dry thoroughly and then preferably coated inside with a thin coat of liquid petrolatum, which is found to be much better than oil. A thinly prepared paste of plaster is poured into it at the outer brim and allowed to harden. The best results are obtained by setting the mold into a small pasteboard box in which it is held in proper position and prevents the thin plaster from running over the depressed edges. By gently tapping the mold when the cast has set, it is made to separate from the latter sufficient to permit of separating or cutting away of the mold inside of it. The cast, when removed and dry, is coated with white shellac varnish. Upon its reverse side a note is scratched into it, giving the case number, or such information as the surgeon may desire.