1880.] 



On the Solubility of Solids in Gases. 



485 



containing potassic iodide in solution was higlier than pure alcohol, 

 but subsequent experiments determined me to go into the matter again. 

 The cause was this. I found that absolute alcohol if exposed to air 

 for a very short time takes up sufficient moisture to alter its critical 

 point ; and I considered that in preparing the solution of the iodide 

 some moisture might have been introduced. The-experiments were 

 repeated in the following manner. Some common absolute alcohol 

 was placed in a flask with caustic lime, freshly burned, and cohobated 

 for a week. The flask was then fitted with the arrangement shown in 



the diagram. The tube connected with the drying arrangement is 

 turned up at the lower end, so that the exit tube may be slipped into 

 it. A current of air desiccated over sulphuric acid is passed through 

 this for some time, and the tube A then slipped out of the recurved 

 end in the flask, turned round so as to clear it, and pushed down till it 

 is below the level of the desiccated alcohol, which is forced up into 

 the experimental tube sealed or connected to A. In this way, any 

 quantity of alcohol, which has never been removed from contact with 

 lime, can be introduced into the working tube. A portion of fused 

 potassic iodide placed in the experimental tube before the experiment 

 enables a saturated solution to be prepared out of contact with air 

 when the liquid is sealed up. Twenty experiments were done with 

 pure alcohol, and twenty with alcohol saturated with potassic iodide. 

 The pure alcohol had the specific gravity "7928 at 15 0, 5. 



Alcohol Alcoholic sohi- 



alone. tion of iodide. 



Mean temperature 234"3 235'1 



Probable error of single experiment 0'62 .... 0*50 



Mean pressure 64*5 .... 65*8 



Probable error of single experiment 0*83 .... 0*95 



These numbers are very much closer than the former ones, and go 

 to show that with proper precautions the critical point is very slightly 

 raised indeed by the introduction of a minute quantity of solid. Were 



2 m 2 



