STANDARDIZATION AND EFFICIENCY OF THE FOG CHAMBER. 23 



To facilitate comparison with the later work, where mercury light is 

 used, a series of coronas in geometric sequence is given in table 9, in which 

 the Welsbach mantle still furnishes the light. Here 5 denotes the chord 

 of the angular diameter of the coronal disk on a radius of R = 30 cm. , when 



?0 18 16 



FIG. 3. Charts for white light (Welsbach burner), -?/3> f the reddish edge of 

 the disk of coronas, in terms of a number, z, of the successive identical partial 

 exhaustions in the series. 



FIG. 4. Charts for green mercury light, showing the coronal apertures, 5/30, 

 of the edges of the greenish disks of coronas, in terms of the series number 

 2 of the partial exhaustions. Series I for 2-minute intervals between 

 exhaustions, series II for i -minute intervals. 



