THE STRUCTUKK OF THK NUCLEUS. 



91 



TABLE 17— NUCLKI DUE TO SHAKING PURE WATER. 



The nuclei are nearly pure water globules, which speedily evaporate. 



Let a small quantity of sodic carbonate be added to the watei'. The result is 

 a pheiKiiiieoal increase in the persistence of the nuclei. Table 18 containing data 

 obtained by shaking the solution shows this. 



TABLE 18.— NUCLEI DUE TO SHAKING A DILUTE SOLUTION OF 



SODIC CARBONATE. 



Violent shaking. Initial apertures vary from i.4°-2.o', depending on the violence of shaking. 



The size and persistence depend on the violence of shaking, but coronas may still 

 be obtained even after 15 houi's. 



The body iu solution in this case is a solid. One is liable to conclude that the 

 persistent nucleus is the solid residue left after evaporation. This is not true. 

 The nucleus, both hei-e and in the above experiments with hydrocarbons, etc., is a 

 concentrated solution. 



To decide the question as to the cause of the indefinite persistence of the 

 nuclei produced by shaking, it is necessary to test a chemically dissolved gas, like 

 H CI or HgN. Pure water was first taken and the evanescence of nuclei confirmed. 

 Pure H CI was now added in small quantity, and the following marked degree of 

 persistence established : 



