[miller] chemical LABORATORY RESEARCHES 267 



a maximum when the ratio of monosulphide sulphur to dissolved 

 (polysulphide) sulphur is about 1 to 1.7, and then falls ofif to zero 

 as the solution approaches saturation with sulphur. These results 

 have an important bearing on the theory of periodic phenomena 

 at the anode discovered by Kiister. 



The Reactions of Zircon in the Electric Furnace 

 By I. M. Logan, B.A.Sc. 

 Presented by Professor W. Lash Miller, F.R.S.C. 



Heated in shallow graphite trays in a resistance-type crucible 

 furnace to 1800°, zircon is converted into silica and zirconium oxide; 

 this reaction may be observed at temperatures as low as 1600°. 



Heated with carbon, it is converted into zirconium carbide 

 mixed with a small proportion of zirconium silicide. Heated with 

 silicon in a carbon crucible in the high frequency induction furnace, 

 much more carbide than silicide is formed. Heated in an atmosphere 

 of nitrogen, in a shallow graphite dish, fumes of silica are given off, 

 and the residue contains zirconium carbide but no nitride. 



These experiments were carried out under the direction of 

 Professor J. T. Burt-Gerrans. 



The Characteristics of Electric Furnace Arcs 



By A. E. R. Westman, B.A. 



Presented by Professor W. Lash Miller, F.R.S.C. 



An arc "characteristic" is a curve shewing the relation between 

 current and voltage for an arc of constant length; it depends on the 

 material of the electrodes, that of the cathode usually being the more 

 important. Mrs. Ayrton has determined the characteristics of arcs 

 between carbon electrodes up to half an inch in diameter, and cur- 

 rents up to thirty amperes; practically no work has been done with 

 heavier currents or larger electrodes. In the present investigation 

 currents up to nine hundred ampres were employed. 



