86 



A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



heat of steam is considered constant (Regnault's vakie, 606 at 0° C), and the 

 ratio of specific heats is 1.4 1, the following values may be derived: 



For (J/' =22; 0=10 7n = 4.2X10 * 



20 5.5 



30 6.7 



Fori?/' = 8. 5; 6'=io )M =21X10"* 

 20 26 



30 28 



The effect of a rise of temperature on latent heat would be an increment of 

 the order of .05 per cent, per degree. The specific heat ratio is also variable, 

 and for lack of data applying to the region of low temperature in qtiestion these 

 subsidiary variations mtxst be disregarded. 



If the data for dp=i'j above be included, a table of double entry may be 

 drawn up adapted for all pressure differences between 8 and 22 cm. and for 

 temperatures between 10° and 30°. 



The optic constant in the two cases becomes (since n = 6ms-'/7ra^) 



For 6p = 8.^ cm., « = i225' (diffraction) and » = 202.'>' (subsidence). 

 For Sp = 22 cm., n = 284s' (diffraction) and h = 4705'' (subsidence). 



Finally the volume ratio, y, is at ($^ = 8.5, 



J'= (57-7 -8.5)/(75-6- 17-9) = -853. 



and at Sp = 22 cm., 



>'= (73-7 -22.2)7(76.0- 2.3) =.700, 



with which values a practical table is appropriately drawn up, time losses being 

 ignored as above. 



The subsidence constant computed for the different series shows the same 

 falling off of value just before the coronas vanish, to which attention has already 

 been called. The following cases may be instanced. 



TABLE 12.— VALUES OF S FOR SMALL CORONAS. 



