2 HUTTON, Frisian of Quart :i in the Electric Furnace. 



results. The process is, however, expensive, and is also 

 very slow, since the oxyhydrogen flame is at a tempera- 

 ture only slightly above the fusing point of silica, and, in 

 fact, it is only at a certain point in the flame that the 

 fusion can be carried out at all. 



Moissan^ has studied the effect of the electric arc 

 upon silica, and has noted that it fuses and is easily 

 volatilised, but he studied more particularly the reduction 

 products, carborundum and silicon, which remain behind 

 when silica is heated for some time in an electric furnace, 

 and, according to Gautier, did not succeed in making 

 apparatus of this material. Upon repeating Moissan's 

 experiment on the volatilisation of flint stones as a lecture 

 experiment, with an electric-arc furnace using 300 amperes 

 at 50 volts, I was struck by the appearance of the residual 

 unvolatilised silica, which was very glassy and in parts 

 quite transparent. Experiments soon showed that, pro- 

 vided a small current of air is allowed to pass through 

 the furnace, no reduction of the solid or liquid silica takes 

 place, and, consequently, the arc can be used as a source 

 of heat for fusing silica without fear of reduction spoiling 

 the results. 



At first apparatus was fitted up for obtaining an 

 arc-flame from inclined carbons by magnetic deflection 

 downwards ; in this way the arc-flame was made use of 

 much in the same manner as the oxyhydrogen flame, and 

 rods could be made easily by the method recommended by 

 Shenstone. It was soon found, however, that a small arc 

 using 15-20 amperes was not sufficiently powerful to 

 ensure rapid work, and, after working with a similar open 

 arc, using about 50 amperes with separate circuit for the 

 magnet, the furnace was again brought into use for fusing 

 the quartz. 



' H. Moissan. " Le Four clcctrique," 1S97, p. 49. 

 A. Gautier, loc.cit. 



