348 Messrs. C. Tomlinson and G. Van der Mensbrugghe [May 16, 



with the addition of a bit of caustic potash, was boiled and filtered into four 

 clean flasks. When cold, a drop of castor-oil was deposited upon the 

 surface of each of the solutions. It flattened at first, but soon recovered the 

 lenticular form. There was no nuclear action during an hour. On gently 

 shaking the flasks, the oil was diffused through the solution without nuclear 

 action. 



In an experiment described in Part II. fragments of stearine were scraped 

 into a solution with immediate nuclear action. In such a case, the stearine 

 furnished the film-forming material that produced the solidification of the 

 solution. The solution was boiled with the stearine in it ; and in cooling 

 the stearine formed into solid disks without nuclear action, although the 

 flask was frequently shaken. In this case the boiling solution had sapo- 

 nified 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 turpentine 

 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 imme- 

 diately became solid. The turpentine was now distilled, and a drop of the 

 distillate was deposited on a similar solution, when it formed a well-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 measuring 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 action as 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 liquids 

 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 anyone of them, according to the theory, ought to spread 

 on the surface of a solution where £ = 5*2, and not in all cases spread on 

 the solution of which t = 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 



