IOO 



VAPOR NUCLEI AND IONS. 







Fig. si. 



Fig. 50. Section of inclosed steam jet and tube. 

 Fig. 51. Binocular inclosed steam jet. 



Fig. 52. Chart showing margin of opaque zone for different steam pressures (pounds 

 per square inch) and temperature of inflowing air. 



nection with similar color effects. But the case of the steam jet may 

 be duplicated, in different ways, by the vapors of typical non-ionizing 

 liquids, like gasoline, benzol, carbon bisulphide, etc., with even more 

 saturated axial colors than are observable in steam. Electrical resonance 

 can not, therefore, be effective here, where the fog globules are dielectric. 

 The particles, moreover, are too large to fall within the lines of such 

 an explanation. 



Returning to the diagram (fig. 52), it will be seen that at a temperature 

 of about 40 there is no observable condensation; in other words, the 

 steam passes through the tube like a gas, leaving the field quite clear. 

 At 40 , therefore, the supersaturation at which condensation begins to 

 take place on the nuclei of dust-free air is just reached; below it, at the 

 given pressure, the supersaturation is in excess, and steam pressure 



