A practical treatise on artificial crown- and bridge-work . model and articulation made to facilitate the subsequent con-struction. Dr. Knappa method of constructing bridge-work is similar tothat in general use except in the investing and the soldering ofthe parts together, the latter being done with the blow-pipe in amanner similar to that above described. Figs. 470 and 471 illustrate specimens. Dr. Knapps compound blow-pipe (Fig. 472) consists of aminiature blow-pipe in which the ordinary illuminating gas(carburetted hydrogen or coal-gas) flame is combined with acurrent of nitrous oxide from
A practical treatise on artificial crown- and bridge-work . model and articulation made to facilitate the subsequent con-struction. Dr. Knappa method of constructing bridge-work is similar tothat in general use except in the investing and the soldering ofthe parts together, the latter being done with the blow-pipe in amanner similar to that above described. Figs. 470 and 471 illustrate specimens. Dr. Knapps compound blow-pipe (Fig. 472) consists of aminiature blow-pipe in which the ordinary illuminating gas(carburetted hydrogen or coal-gas) flame is combined with acurrent of nitrous oxide from a cylinder of the condensed combination of these gases in combustion forms essentially 230 ARTIFICIAL CROWN- AND BRIDGE-WORK. a carbo-oxyhydrogen By means of a yoke and set-screw, the valve of the cylinder is connected with the tubes andvalves of the blow-pipe, so that the proportions of the mixture Fig. 1 The ordinary compound oxyhydrogen blow-pipe flume is produced by2 volume* of hydrogen ; 1 volume of oxygen. Carburetted hydrogen consists of 2 volumes of hydrogen ; 1 volume of carbon. And nitrous oxide of - volumes f hydrogen ; 1 volume of oxygen. Consequently Knappa blow-pipe flame is produced by a mechanical mixture of2 volumes of hydrogen ; 1 volume of oxygen ; 1 volume of carbon. DR. KXAPPS METHODS. 231 of nitrous oxide and the illuminating gases are under perfectcontrol. The flame-jet can be diminished to half an inch inlength, and at that size will melt a small piece of gold plate. This blow-pipe is useful for many purposes in the laboratory ofthe present time, especially in forming solid gold backings todummies for bridge-work, strengthening seamless gold crowns,and forming solid gold crowns. Dr. Knapp has exhibited to the profession some very finespecimens of crown- and bridge-work, and presented much thatis novel and interesting, as well as encouraging to the artis
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherphila, bookyear1889
