90 



THE STRUCTURE OF THE NUCLEUS. 



Tlie mu'lei prinluced by shaking methyl alcohol were incidentally exaniimd 

 anil found to persist over 30 minutes after shaking. The occurrence of traces of 

 imiinrity is again to ])e inferred, for the results below will show that only in oases 

 of absolute purity can the imme'liate decay of these nuclei be expected. 



29. Acetone. — This le-agent must be classed with the ionizing solvents, and 

 vet the coronas obtained are identical in character witli those peculiar to the uon- 

 ionizinc solvents above. There is stiong distortion of both foiin and coKir, a.s the 

 following tal)le of coronas shows: 



TAHI.E i6.— liKHAVIOR OF PHOSPHORUS NUCLEI IN ACETONE VAPOR. 

 EXHAUSTION, 76-590111. PERIODS BETWEEN EXHAUSTIONS USUALLY 3"'. 



lixliauslion No. 



Coronas. 



10 

 I I 

 12 



'3 



Wli, rd ; subsides rapidly 



VVh, rd and wh, \n\i. Distortion 



Red l)elow, blue bands above 



ti (( it (I i( 



Nuclei near bottom 



Corona below, rises as exhaustion proceeds, then at top 

 Strata below 

 Strata rise from bottom 

 Strata only 5 cm. high 

 Longer periods between exhaustions 

 At 50'", strata 7 cm. high 



65'", fog 15-20 cm. high, corona nearly full 



73'", fog 5-10 cm. high, faint 

 Etc. 



One may note that when time is allowed for diffusion, the coronal pattern eventually 

 becomes regular again. 



The coronas due to shaking persist as usual. Observations made 44"' and 45'" 

 after shaking, brought out strong, multi-annular forms. 



30. Water. — In the light of the above observations the corresponding behavior 

 of watei- is ln'ought forward with renewed interest. Water has the addition.nl 

 advantage of being less liable to contantination in ap[)aratus of which rtibber 

 tuliing is an essential part, than the hydrocarbon solvents. Aqueous solutions will 

 therefore be treated at length in the next chapter. Here I will merely add certain 

 results, not found in the same connection there, for completeness. 



If all precautions be taken to insure clean and new apparatus and appurte- 

 nances and perfect filtration, the air above the water, if free from nuclei, remains .so 

 indefinitely. Spontaneous nucleation does not occur. One is liable to be led 

 a.stray, however; thus a connection of rubber tubing through which vapor of 

 carbon disulphide has passed, is an abun<1ant source of nuclei for days after. 



If a clean ves.sel, free from nuclei and charged with pure water, is vigorously 

 shaken so as to comminute the water, nuclei are produced in considerable (piantity. 

 But the nuclei are short liveil, as seen from the following table: 



