288 Dandeno : Osmotic theories 



from these he calculated what the pressure would be for stronger 

 solutions. Supposing we assume that Pfeffer meant to say ''342 

 grams in i liter solution'' (and this is the only statement tenable 

 if we are to harmonize it with van't Hoff's theory), we are led to 

 an important conflict with Morse's actual experiment which shows 

 that a solution containing 342 grams of cane sugar per liter (of 

 solution), gives over 31 atmospheres pressure. We then arrive 

 at this paradox — theoretically ^i\\G: pressure should be 22.4 atmos- 

 pheres; actually, it is over 31 atmospheres. This pressure of 31 



r 



atmospheres was actually obtained. In fact the pressure was 

 more than this, but the apparatus (osmometer) burst at this enor- 

 mous pressure, and the pressure may therefore be considered 

 more. They conclude that a pressure of at least 32 atmospheres 

 would result from a volume-normal-solution of cane sugar (342 

 grams per liter of solution). 



The actual difference in volume between a solution made by 

 dissolving 342 grams of cane sugar in one liter of solution, and 

 that made by dissolving 342 grams of it in one liter of water is 

 about 214.4 c-C- Ii^ the first case the volume is 1000 c.c. and in 

 the latter the volume is 12 14.4 c.c. 



The following experiment shows also that the gas-pressure 

 theory is not tenable. Pour a few c.c. of chloroform into a test- 



r 



tube, then drop into this a crystal of iodine. The chloroform 

 turns red from the dissolved iodine. Now pour very gently on top 

 of this a few c.c. of water, and on top of the water a few c.c. of 

 xylol to which has been previously added a crystal of iodine. The 

 xylol dissolves the iodine and so we have one red liquid on top, 

 and one on the bottom of the water. The water remains clear for 

 days, weeks, and months, showing that none of the iodine passes 

 from either the xylol or the chloroform to the water. According 

 to the gas theory, it should do so. But if we carefully suspend 

 by a wire, a crystal of potassic iodide in the water, then, after a 

 short time, the iodine coloration is seen in the water. Some of the 

 iodine has left one or other, or both neighboring liquids. The ex- 

 planation of this is that the KI solution attracts the molecules of 

 iodine from the other solutions. They are attracted to not forced 

 from."* Morse gives the following expression which applies to 



*Am. Chem. Jour. 34: 91. 1905. 



