92 THE STRUCTURE OF THU NUCLEUS. 



TABLE 19— NUCLEI DUE TO SHAKING DILUTE HYDROCHLORIC ACID. 



Time elapsed after shaking. 



•5'" 

 10" 



Corona. 



Strong. (/=.oo25 cm. 

 Distinct but weak 



Tested with pure water again, the fleeting coronas persisted somewhat longer 

 (10 minutes), showing that traces of H CI still lingered in the clean ai)paratus. 

 On a^'aiu adding H CI, the above results were confirmed. 



Dilute ammonia was ne.xt tested in the same way. Great care had to l>e taken, 

 even after the vessel was thoroughly cleaned, to remove the last traces of II CI. 

 When this was done, air free from nuclei remained so above dilute ammonia 

 indefinitely. Spontaneous nucleation does not occur. On shaking, however, the 

 ammonia nucleus behaved like the IICl or the NaCOg nucleus, showing long 

 persistence. 



TABLE 20.— NUCLEI DUE TO SHAKING DILUTE AMMONIA. 



With these experiments, the indefinite persistence of the nuclei produced by 

 shaking solutions, apart from the loss by diffusion, may be considei-ed established, 

 no matter what may be the oiiginal state of aggregation of the solute. It is next 

 necessary to inquire into reasons. 



