A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



93 



DIFFERENT SPEEDS OF EXHAUSTION FOR THE GIVEN PRESSURE DIFFERENCE. 



33. Increased suddenness of condensation. — As a final test of the trust- 

 worthiness of the above sequences, it was necessary to repeat the results with 

 some form of valve more nearly instantaneous in its action. In the case of 

 air nuclei, special comparisons instanced below (Chap. IX, § 3 ) showed that 

 for a reasonable relation between the sizes of the condensation chamber and the 

 vacuum chamber, an ordinary plug stopcock was quite as serviceable as an 

 instantaneous \'alve, the coronas obser^'-ed with the air nviclei being in both 

 cases the same. With phosphorus nuclei and at the outset of the experiment, 

 however, this is not quite the case, at least when the nuclei are very numerous 

 and very small. 



The design of the new valve was very simple. In figure 3, p. 58, V leads to 

 the vacuum chamber (large aspirator flask) , and C to the condensation chamber. 



TABLE 18.— THREE GEOMETRICAL SEQUENCES OF CORONAS, FOR INSTAN- 

 TANEOUS VALVE. CHAMBER, 20 X 26 X3S cm.^ DISTANCES, 85 AND 250 cm. ; 

 ^=22°; BAROM., 74.9; (J/)=i7 cm.; >'=.767; p = o; S=2.i; 5' = i.9s; a (SUBSI- 

 DENCE) = .0029; w = 4.8Xio-'?,- m' = 3o8ooo; «„ = 340000; PHOSPHORUS NUCLEI ; 

 WELSBACH LAMP, AND .t MEASURED TO OUTER EDGE OF RED RING. 



First Series. 



