TRANSACTIONS OF SECTION B. 521 



The chemical results were : — 



(/) So long as the air resistance is very high, the chief modification in the 

 air is the production of ozone ; but with a gradual breakdown of the 

 air resistance oxides of nitrogen are formed, though this change does 

 not appear to depend upon the temperature of the apparatus, as might 

 have been expected. 



{g) The gas yielded is always in a state of ionisation ; but the higher the 

 air resistance, the less marked is this ionisation. 



(A) Contrary to the statement of many authorities, ozone and oxides of 

 nitrogen are found to exist side by side without mutual destruction. 



(i) The bleaching action of the gas appears to be due to oxidation. 



Biological tests showed clearly the marked sterilisation produced in flour by 

 means of the gas. 



The authors in a summary gave the conditions which should be aimed at for 

 economical production of ozone and oxides of nitrogen respectively; suggesting 

 that no very high temperature is necessary for the latter. 



2. The 1:3: 5-hexatrien. £i/ Professor Van Rombuegti. 



3. Report on Dynamic Isomerism. — See Reports, p. 157. 

 4. Report on the Study of Hydro-aromatic Substances. — See Reports, p. 257. 



5. On the Effects upon the Concentration of a Solution of the Presence 

 of an Excess of Undissolved Salt. ^^ A. Vernon Harcoubt, F.R.S. 



A paper has recently appeared in the Transactions of the Chemical Society on 

 the attractive force of crystals for like molecules in saturated solutions, in which 

 the author gives an account of experiments which lead him to believe in the 

 existence of such a force. The experiments consist in charging pairs of flasks 

 with saturated solutions of various salts, and adding in one case a quantity of the 

 salt which remained undissolved. The flasks were loosely plugged with cotton- 

 wool, and placed in a cellar where they stood for a number of days, after which 

 the concentrations of the two solutions were determined by evaporation over the 

 water bath, or by taking their density. These experiments appearing to be incon- 

 clusive, a further experiment on the same point was made by the present author. 



A probable source of error in such experiments arises from variations in the 

 temperature of the solutions and evaporation of water. When from either cause 

 crystallisation is taking place, it wiU proceed more rapidly in presence of a larger 

 quantity of undissolved salt ; and if in this phase portions of the two solutions are 

 withdrawn for examination, that which contains the undissolved salt will be 

 found to be the weaker of the two. 



To avoid error from this source the author chose sodium chloride, whose 

 solubility varies very little with temperature, as the salt to be tried, and corked 

 the two flasks containing the saturated solution to which had been added (1) a 

 large quantity, (2) a very small quantity, of the pure salt. They were allowed to 

 stand many hours, with occasional inversion, in a large vessel of water in a room 

 of steady temperature. 



A portion of each liquid was then removed, weighed, and evaporated to dry- 

 ness ; the residual salt was further heated and then weighed. 



(1) 5*9941 grams of solution contained 1*6739 oi salt, 



(2) 5-9986 „ „ „ „ 1-6756 „ 



giving in both cases "2626 gram of salt in one gram of solution. 



A repetition of this experiment gave in one case '2623, in the other "2620. 

 The effect of the undissolved salt does not appear to be measurable. 



