Electrochemical and metallurgical industry . FIG. 5—FlSED QI ARTZ TI BE June, i<;o5.] ELECTROClIE^[ICAL AXD ^[KTALTAR^,TCAL INDUSTRY. 217 taiiily was \ery liigh, and therefore tlicre was a \erj rapidvaporization of the sihca, and the vapor produced reacted withthe carbon of the resistor, forming sihcon carbide. Carefulmeasurement showed that this did not appreciably alter thediameter of the resistor, the silicon carbide apparently takingtile place of the carbon on the outside of the resistor. A fairsized piece of the resistor was heated in oxygen to remove all. FIG. 6.—QU.\RTZ TUBE AND RESI
Electrochemical and metallurgical industry . FIG. 5—FlSED QI ARTZ TI BE June, i<;o5.] ELECTROClIE^[ICAL AXD ^[KTALTAR^,TCAL INDUSTRY. 217 taiiily was \ery liigh, and therefore tlicre was a \erj rapidvaporization of the sihca, and the vapor produced reacted withthe carbon of the resistor, forming sihcon carbide. Carefulmeasurement showed that this did not appreciably alter thediameter of the resistor, the silicon carbide apparently takingtile place of the carbon on the outside of the resistor. A fairsized piece of the resistor was heated in oxygen to remove all. FIG. 6.—QU.\RTZ TUBE AND RESISTOR. free carbon, and the residue was found to consist of siliconcarbide. The carbide at the outer part of the resistor wasleft in the form of a solid ring (Fig. 7) or cylinder with anaverage thickness of imm., while the carliide from the in-terior of the resistor was in the form of powder. The ash inthe carbon amounted to per cent, while in the originalresistor it was only per cent. The approximate amount of silica vaporized from the in-terior of the tube and combined in the carbon as silicon car-bide may be calculated from the figures given above. Thetotal weight of the resistor afifected amounted to 108 grams,and from the analysis it is found that the silicon carbide pres-ent amounts to grams, corresponding to grams ofsilica. This phenomenon of the vaporization of silica and for-mation of silicon carbide is important, since it has a markedeffect on the resistance of the resistor. Thus, at the end ofthe first rim, the resistance of
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