THE STRUCTURE OF THE NUCI-EUS. 



39 



-' = l^(f + |lo|.)=-95^ 



iind 1—3?= .046 grams of water obtained from each gram of vapor. Thus 17.2 

 X 10" ^ X.046 = 790 X 10"^ gi'ams of water se])arate out per cub. cm. of moist air. 



17. Numerical valves. — One observes in passing tliat if 5 x 10* nuclei ai'e 

 present per cub. cm., of the saturated emanation, the iiuml)er iirfei'red in the first 

 volume of these researches, then (790 X 10-9)/(5 X 10*) = 16 X IO-12 cub. cm. 

 is the volume of each water particle or al)out .OOO-iT) cm. its diameter at the outset. 

 This agrees very well in order with the i-esults obtained directly for coronas below. 



To find iVin the tables, the eq'uation 



iy^=io 



s(i +/;/)iog.v 



is given by experiment, where y is the ratio of densities after and Ijefore any ex- 

 haustion. Hence since initially S = 293", |? = 76 cm., and finally S'= 273° and js' 

 = 58 cm., 



11=1 J^ — ■?^' = 5'^ X ^93 _ §19 

 P p/^ 76 X 273 



Again the interval of time, /-, between the exhaustions, is on the avei'age 1.65 



minutes in table 9, 1.61 minutes in table 10, 1.74 minutes in table 11, 1.75 minutes 



in table 12. Consequently, for tables 9 and 10 



.7 007 Z 



^^^,-(:.:63)X.o866^^^ 



m 



ay be assumed, and in tables 11 and 12 



i\r =, 10 -^ ^'■'")x. 0866^^^^ -.1017 . 



is the corresponding equation. With these constants the values, N, of the tables 

 were computed. 



IS. Relative size of cloud imrtides. — ^ Assuming that the same amount of 

 vapor is condensed per cub. cm. in each expansion between fixed pressures of the 

 moist ail- in the receiver, the lelative size of particles may be computed for the 

 given orders of coronas. If the size of the particles of any one oi'der is known, all 

 WMiuld be found absolutely. It is only after about 20 exhaustions that the ordinary 

 uoimal coronas are encountered. The next table (13) contains an example of typi- 

 cal cases. It shows that there is not a striking variation of diameters to correspond 

 with the startling: variation of coronas. These are there foie a lather sensitive cri- 

 terion of the changes of diameter of the cloud particles. 



TABLE 13.— RELATIVE SIZE OF CLOUD PARTICLES. 



