524 Day and Sosman — Nitrogen Thermometer Scale 



from the normal gradient (without heat in the upper coil) to a 

 temperature equal to that of the sulphur vapor itself. 



None of these changes produced any measurable change in 

 the temperature of the sulphur vapor as recorded by the gas 

 thermometer provided enough heat was supplied to fill the 

 tube with vapor. During some of the measurements the vapor 

 escaped freely between the glass tube and aluminium cover and 

 burned there. 



The remaining details and relative dimensions of the sulphur 



Fig. 3. 



Fig. 



3. Apparatus for direct determination of the boiling jDoint of sulphur 

 with the nitrogen thermometer. Scale : 1 to 6"5. 



vapor bath will be clear from the diagram (fig. 3), which is 

 drawn to scale. The arrangement shown in the figure is the 

 one with the aluminium shield. 



The sulphur used was distilled to free it from a black residue 

 which was found in both of two different preparations of C.P. 

 sulphur. This residue, which is partly if not wholly ferrous 

 sulphide, would probably have had no appreciable effect on the 

 boiling pcnmt. After the close of these experiments the 

 sulphur boiling apparatus was sent to the Bureau of Standards, 

 where a number of measurements were made of the tempera- 



