on Supersaturated Saline Solutions, 229 



In this case tlie boiling solution had saponified or otherwise removed 

 the film-forming matter, or, in other words, had made the stearine 

 chemically clean. 



There is also a difficulty in the case of oil of turpentine, as in the 

 following experiment : — 



Experiment 9. A drop of an old but clear and bright oil of tur- 

 pentine was deposited on the surface of a solution containing 2 parts 

 of salt to 1 of water. The drop flashed out into a film, and the 

 solution immediately became solid. The turpentine was now distilled, 

 and a drop of the distillate was deposited on a similar solution, when 

 it formed a w^ell-shaped lens with no nuclear action, although the 

 flasks were left out during several days. 



Now the tension of the old oil first used is =2*2; and had the 

 effect of distillation been greatly to exalt the tension, the experiment 

 would have been intelligible according to the theory ; but on mea- 

 suring it the tension was found to be only 2*4. 



A somewhat similar case is given in Part II., in which an old 

 oil of bitter almonds was strongly nuclear, while the same oil freshly 

 distilled had no such action, but became converted into benzoic acid, 

 still without any separation of salt. After some days, to prove that 

 the solution was still supersaturated, it was touched with an unclean 

 wire and it immediately became solid. 



Still, however, there are such a large number of cases in which oils 

 and other liquids spread upon the surface of the solutions with nuclear 

 actionas to justify the labour bestowed upon the theory by one of us 

 during the last six months. Many of these cases are stated in Part II. ; 

 but a few of them may be repeated here for the sake of comparing 

 the action of such hquids upon solutions of different strengths, which 

 was not done before. 



If we take a number of oils, the tension of which varies from 

 about 2*5 to 3-5, a drop of any one of them, according to the theory, 

 ought to spread on the surface of a solution where t = 5'2, and not 

 in all cases spread on the solution of which ^ = 4. 



Experiment 10. Twelve flasks, containing a solution of 1 part salt 

 to 1 of water were prepared, and a drop of each of the following oils 

 formed films with immediate crystallization of the solutions, viz. 

 pale seal-oil, sperm-oil, cotton-seed oil, and niger-oil. A drop of 

 linseed-oil formed a lens ; but this soon becoming ragged, crystals 

 diverged from it. A drop of castor-oil formed a lens with no nmclear 

 action. 



Experiment 11. Three of the above solidified solutions were heated 

 over a lamp, boiled, and covered over. The oil collected on the sur- 

 face in innumerable small disks. Next morning one of the solutions 

 was found crystallized, and the other two became solid on gently 

 agitating the flasks. 



In this case as the solutions cooled down or were gently agitated 

 the disks spread out into films with nuclear action. 



Experiment 12. A solution of 3 parts salt to 1 of water was 

 filtered into twelve flasks, when a drop of each of the following oils 

 deposited on the surfaces of the solutions became lenticular without 



