On the Refraction of Fluorine. 481 



large and small grains, that the forces between the bodies 

 would be proportional to the product of the volumes divided 

 by the square of the distance ; i. e. that the state of stress of 

 the medium may be the same as Maxwell has shoAvn must 

 exist in the aether to account for gravity. We have thus an 

 instance of a medium transmitting waves similar to heat-waves 

 and causing force between bodies similar to the forces of gra- 

 vitation and cohesion, in such a manner as to constitute a con- 

 servative system. More than this, by the separation of the two 

 sets of grains, there would result phenomena similar to those 

 resulting from the separation of the two electricities. The 

 observed conducting power of a continuous surface for the 

 grains of a medium closely resembles the conduction of elec- 

 tricity. And such a composite medium would be susceptible 

 of a state in which the arrangement of the two sets of grains 

 were thrown into opposite distortions, which state, so far as it 

 has yet been examined, appears to coincide with the state of 

 a medium necessary to explain electrodynamic and magnetic 

 phenomena according to Maxwell's theory. 



In this short sketch of the results which it appears to me 

 may follow from the recognition of the property of dilatancy, 

 I have not attempted to follow the exact reasoning even so 

 far as I have carried it. 



In the preliminary acceptance of a theory the mind must 

 be guided rather by a general view of its adaptability than 

 by its definite accordance with some out of many observed 

 facts. And as it seems, after a preliminary investigation, that 

 in space filled with discrete particles, endowed with rigidity, 

 smoothness, and inertia, the property of dilatancy would cause 

 amongst other bodies not only one property but all the fun- 

 damental properties of matter, I have, in pointing out the 

 existence of dilatancy, ventured to call attention to this 

 dilatant or kinematic theory of aether without waiting for the 

 completion of the definite integrations, w r hich must take long, 

 although it is by these that the fitness of the hypotheses 

 must be eventually tested. 



LVIII. On the Refraction of Fluorine. 

 By George Gladstone, F.C.S* 



IN his paper on the Refraction-Equivalents of the Elements, 

 published in the Phil. Trans, of 1869, Dr. Gladstone 

 estimated the equivalent of fluorine at 1*45, from the results 



* Communicated by the Author, haying been read at the Meeting of 

 the British Association at Aberdeen, September 1885. 



