328 Mr. C. Tonilmson on the Action of Nuclei. [Nov. 20, 



what is the peculiar function of ozone in rendering oils, &c, active, as 

 nuclei ? 



It is evident, from the behaviour of ozone on volatile oils exposed to 

 its influence that its action is an oxidising one, diminishing their 

 cohesion, just as rust weakens the cohesive force of the particles in a 

 bar of iron. 



The effect which ozone produces quickly on a volatile oil is pro- 

 duced slowly on the same oil by long keeping. Its cohesive force is so 

 far weakened, if not destroyed, that a drop of it on the surface of a 

 solution no longer tends to assume the lenticular form, or to disperse 

 in globules through the solution. Under such circumstances, since oil 

 adheres much more strongly to salt than to water, and the super- 

 saturated solution, being a highly charged system, capable of yielding 

 to a force that is exerted in the right direction,* such an oil is capable 

 of adhering to, and separating, a portion of the salt, and the action, 

 once begun, is propagated rapidly, until the whole solution is solid. 



The action of a foreign nucleus introduced into the cold solution 

 from without, is to determine the formation of the ten-atom or 

 normal salt : but if a solid body be boiled up with the solution, and 

 the covered flask be left to cool to temperatures about and below 

 40° F., the modified or seven- watered salt will be found clustered 

 about the solid body. An explanation of this may be found in the 

 behaviour of the salt while undergoing solution. Suppose the flask 

 to contain six parts of the crystallised, not effloresced, salt and three 

 of water. If the heat be applied too strongly, the salt gives up its 

 water of crystallisation, and the anhydrous salt is thrown down, and 

 produces violent bumpings of the flask. But if the heat be kept 

 below the temperature of maximum solubility of the salt (about 93° 

 F.) until the whole of it is dissolved, the solution may be raised to 

 the boiling point and also be cooled down in covered vessels to about 

 40° F., without any separation of salt. The anhydrous salt now 

 appears to be in solution,f and a solid body previously heated in the 

 solution forms a portion of it, or rather a portion of the flask, and 

 may be regarded as a prolongation of its sides. Under a proper 

 reduction of temperature, crystals of the seven-atom salt will cluster 

 about such a body, but it cannot be said to exert any active nuclear 

 function. It was pointed out by Ziz, as long ago as the year 1809, 



* See a paper " On the Function of the sides of the Vessel in maintaining the 

 State of Supersaturation." " Proc. Roy. Soc.," vol. xxvii, p. 189. 



f See " Chemical News," 3rd and 10th December, 1869. In Wiillner's experi- 

 ments on the elasticity of steam, when sodic sulphate was added to the water, the 

 diminution in the elasticity was found to be proportional to the quantity of dry 

 salt in solution at temperatures from 10° to 100° C. At the point of maximum 

 solubility of the salt no molecular change occurred, or it would have impressed 

 itself on the curve which represented the elasticity of the steam. 



