498 SCIENCE PROGRESS 



that of molecules endowed with various degrees of attractive 

 power. If von Baeyer's argument be so modified that it be 

 supposed that the affinities, instead of being deflected, act 

 practically at their proper angle and more nearly neutralise one 

 another the more nearly they come into parallelism, the angle 

 a at which the affinities meet may be taken as a measure of the 

 free affinity latent in the molecule ; and the larger the angle 

 the greater will be the activity of the compound. Ethylene 

 (dimethylene) from this point of view 



\ 



is an eminently unsaturated compound ; whilst pentamethylene 

 is all but saturated, as the several pairs of affinities nearly 

 overlap, 1 the angle a being reduced almost to nothing. 



Assuming, for the reasons already stated, that the tendency 

 of oxygen is to simulate carbon, it should follow that the 

 activity of the polyhydrone molecules in water diminishes pro- 

 gressively as they increase in complexity : consequently that 

 penthydrone is practically inactive. 



If water consist on the one hand of simple molecules which 

 have a strong tendency to cling together, and on the other of 

 relatively heavy inert molecules, such as those of penthydrone 

 (OH 2 ) 5 , it is easy to understand why it boils at such an elevated 

 temperature as ioo°. 



A point is now reached at which the story becomes exciting 

 it is therefore time to write, " To be continued in our next." 



In conclusion it may be asked, Can water be the subject of 

 an idyl? An idyl has been defined as a poem which has for 



1 This argument will be best understood if a graphic construction be resorted 

 to. For this purpose a number of V-shaped strips, cut to an angle of io9°28', 

 should be made out of cardboard. These are conveniently made three-quarters 

 of an inch wide and the two limits may be each 6 inches long. Lines should be 

 ruled down the middle of each limb ; the cardboard should be perforated 3 inches 

 distant from the point of intersection of the two lines on each strip. By joining 

 such strips together at the perforated points in twos, threes, fours, fives and sixes 

 by means of drawing pins placed head down on the table and then fixing the joint 

 by covering the points of the pins with discs of cork, models are obtained which 

 represent the various systems. 



