362 IMPROVED FLASK FOR VULCANIZINCI. 



of thickness, reproducing at the same time on the 

 lingual surface the exact form of the palate. 



The small piece which I will pass round, was 

 my first trial ; and will show, perhaps, in its un- 

 finished state, better than any explanation I can 

 give, the effect produced by this process. 



The second specimen, which is a fractured one, 

 shows the object clear enough in its finished state. 

 This method is especially advantageous for suc- 

 tion-pieces, and cases of fissure or imperfection 

 in the palate, when a thin substance is most 

 desirable. 



The flask used for the purpose is one introduced 

 by Messrs. Bell & Turner. It is slightly modi- 

 fied for my purpose by the substitution of round 

 guide-pins for the flat lips in the upper part of the 

 body of the flask. 



The method of preparing the model piece is 

 somewhat the same as usual; that is, the way 

 the teeth are mounted in wax, gutta percha, or 

 the like : but instead of placing wax on the 

 palate, this part is left exposed. In just those 

 parts required thicker than the palate, I place a 

 suitable quantity of wax. Instead of pouring 

 plaster on the waxed palate, as usual, to form the 

 plug, it is poured directly on to the plaster cast, 

 which has been prepared with oil, or some non- 

 adhesive material (that supplied by the Messrs. 

 Ash I find the best). After the plaster has set 

 sufficient time, the parts are separated and the 



