Colours of Cloudy Condensation. 



575 



side tube at a constant head. To empty V (M depressed), 

 c, d (communicating with the atmosphere), and /are opened. 



With this apparatus any desired colour may be shown in 

 the colour-tube by adjusting the valve F, and maintained for 

 any reasonable length of time. There is usually little danger 

 of exhausting the phosphorus. 



2. In the following Table I have given several series of 

 results obtained on different days. Different (absorption) 

 tubes, t, were used, and hence the results can only be com- 

 pared by putting the volume of charged air producing blue 

 as 1 litre/minute*. Variations between the series naturally 

 remain because it is impossible at different times to select the 

 same shade of blue from a continuous series. The pressure 

 of the steam-jet is given under p, 6 is the temperature of the 

 air, and SP the pressure-excess of the volume-flask in centims. 

 of mercury. It is superfluous to reduce to standard pressure 

 and temperature. 



Table. — Colour seen in the Steam-Tube and relative number 

 of Particles entering in case of the Annular Jet. 

 "Blue"=l. 





Volume 



p, 9. 





Volume 



P, 0- 

 dP 



Colour. 



per 



Colour. 



per 





minute. 







minute. 





Crimson- 







Crimson ... 



•28 



p=o S cm. 



indigo ... 



•30 



p = Q cm. 



Yellow 



•38 



= 25° C. 



Yellow - 





0=27°C. 



j Green 



•53 





crimson... 



•45 



<5P=5-5cm. 



Blue-green .. 



•69 





Green 



•70 





Blue (light) 



•83 





Blue (light) 



•83 





Blue (full)... 



1-00 





Blue (light) 



•95 





1 Violet 



1-25 





Violet 



1-85 











Blue (full) .. 



110 









> 



Blue (light) 



•95 





Crimson 



•17 



p = 7 5cm. 



Green 



•78 





! Yellow- 

 crimson... 

 Yellow - 



•26 



0=25° C. ; 





In this series large volumes of air 



green 



•37 



i 



relatively poor in nuclei were used. 



Green 



•51 





In the following series the volumes 



Blue-green ,. 



•63 





are smaller but richer. The curves 



Blue (light) 



•77 





a and b of the chart are probably 



Blue (full)... 



1-00 





not identical even for the same 









standard blue. 



i 







These observations are reproduced in the chart (p. 578) by 

 representing the thickness of an air-plate which would on 



* This is the case for air entering the colour-tube in nearly the 

 saturated state. 



