TiiK s'l'iuicriiiji'; oi- tiik nholkus. \2',i 



29. Sulphuric add. Conceidratiov. Time fosses.— The results of tabic 15 

 show no mai-ked peculiarit}-. Acid nnd saline solutes, therefore, conform to the 

 same general behavior. Cf. figure \'l. 



80. Sugarn. Sucrose. Concentration. Time losses. — The following bodies, 

 with the excet)tioii of tartaiic acid, are neutral organic solutes dissolved in water. 

 They are characterized by the common behavior {cf. figure 15) of producing fewer 

 nuclei on the average than the saline and othei' solutes discussed above. The 

 time coefficients are correspondingly large, and the nuch^i, therefore, under the usual 

 conditions very fleeting, in sjjite of the crystalline body in solution. Thus, the 

 cane-sugar solutions of 2 % and .02 % produce but 157 and 51 nuclei, re8])ectively. 

 The time coefficients are 2.5 and 1.2, showing that solutions of 1 ;^ are already very 

 fleeting as to nuclei. Thus, the presence of a solid solute is not a condition essen- 

 tial to the phenomena of the [)resent cha[)ter; in other words, if the nuclei were 

 mere solid residues all solutions of the same strength should behave alike. 



31. Glucose. Concentration. Time losses. — Glucose in table 17 (figure 15) 

 behaves much like sucrose with the nuclei relatively even more fleeting. 



32. Glycerine. Condensation. Time losses. — This stable liquid is (figure 15) 

 even weaker as source of nuclei than the sugars. The absorption velocities of 

 glycerine and glucose compare with those of pure water. 



33. Urea. Concentration. Time losses. — Table 19 shows that urea as asoui-ce 

 of nuclei is weaker than sugar,with which it in other respects compares. Gf. figure 15. 



Results such as these pi'ove, I think, that the hypothesis of the removal of the 

 nuclei by diffusion and absorption is sound. Otheiwise it would be difficult to 

 state why the residue after the evaporation of the solvent becomes ineffective as a 

 nucleus for condensation. 



34. Tartaric acid. Con-centration. Time losses. — -This solid organic body 

 follows the usual rule of producing few nuclei; but, curiously enough, this number 

 varies but little even when the solution has been diluted 10,000 times. Cf. figure 15. 



The time coefficients give evidence of a similarly unexpected behavior, being 

 actually smaller for the .02 % solution than for the 2 % solution. They moreover 

 show a low order of absorption velocities for organic bodies, indicating the occur- 

 rence of nuclei, which are veiy remarkably persistent. 



35. Alcoliol ami pure water. Concentration. Time losses. — The addition of 

 1.6 fc of absolute alcohol to water reduces the number of nuclei generated by shak- 

 ing. The effect is small ; but one may suspect from this that the variations of 

 surface tension have some bearing on the value of n. Thus the surface tension of 

 the above saline solutions is larger than that of water and so is the nucleation 

 observed. On the other hand, dilute alcoholic solutions, according to table 21, 

 o-enerate fewer nuclei on shaking to correspond with their reduced surface tension 

 as compared with watei'. 



At the same time the ahioholized nuclei are clearly more persistent, for the 

 value of h is definitely smaller for the solution even if the nuclei are all very 

 fleeting. Cf. figure 17. 



