302 SELF-PACKING VULCANITE APPARATUS. 



accurate packing, and liable to produce a still 

 more imperfect adaptation to the moutli tlian 

 where the case is a simple one. I would now 

 proceed to the explanation of the method I have 

 adopted. The apparatus consists essentially, first 

 of all, in a modification of the ordinary form of 

 flask. We have here this form of flask [h and Ic, 

 Fig. A), consisting of three parts, the saucer, the 

 intermediate piece, and the top. The distinctive 

 difference that I have made, and the use of which 

 you will immediately see, is in perforating the lid 

 {g, Fig. A), also having an additional thickness 

 added to it. The bottom saucer may remain 

 exactly as we have been in the habit of using it ; 

 the middle portion of the flask must be pierced 

 with two or more holes — -these holes are to serve 

 for the exit Of the superfluous materials in a 

 manner I will show you immediately. The next 

 point that perhaps it is important to call your 

 attention to, is the abandoning the use of gutta 

 percha as a temporary model, substituting wax, 

 or such a combination. of wax and Canada balsam 

 as will make the wax sufficiently plastic and 

 pliable to try in before submitting it to the 

 process of packing. The next portion of the 

 apparatus consists simply of what I may describe 

 in two words as- a syringe with a steam-jacket. 

 This sjrringe (c. Fig. B), is acted upon by a piston 

 or plunger (d). The latter, instead of being 

 forced by direct action of the hand, is forced 



