1880.] Dr. E. J. Mills. On Chemical Repulsion. 



69 



continues, so also does the retardation at their neighbouring edges 

 increase ; the final result being (however long the experiment may be 

 prolonged), that the other diagonal of the square is completely and 

 permanently traced out in a line of no chemical action. 



The above experiments are of fundamental importance, and they 

 obviously admit of endless variety Of this, a few illustrations may 

 suffice. 



If the upper plate have three perforations, situated on the points 

 of a central equilateral triangle, there are three repulsion lines ; these 

 end at the centre of the triangle, where they form a trilocular point, 

 and traverse its sides midway at right angles. 



When the upper plate has four perforations, situated on the points 

 of a central square, there are four repulsion lines ; these end at the 

 centre of the square, where they form a quadrilocular point, and 

 traverse its sides midway at right angles. 



A very beautiful modification of the preceding experiment consists 

 in simultaneously developing a circle from a (fifth) central perforation. 

 This last circle has no means of escape from the surrounding four. 

 The result is, that it eventually forms a square figure bounded by 

 repulsion lines, and having four symmetrically situated repulsion 

 lines at its corners. 



It is easy to demonstrate that the chemical repulsion in these ex- 

 periments does not depend upon flow. Two superimposed triangular 

 plates for instance, in neither of which is any perforation, give three 

 repulsion lines on immersion in dilute hydric sulphate. From each 

 corner a line proceeds midway (if the triangle be equilateral) to the 

 centre. In this effect, diffusion is alone concerned. 



In addition to hydric sulphate and baric chloride, other pairs of 

 reagents may be used with success ; and I anticipate no difficulty in 

 obtaining results in which precipitation is not concerned. A beginning 

 has also been made with experiments in tridimensional development. 



The complete explanation of what I have termed " chemical 

 repulsion," will probably demand a varied and considerable amount of 

 experimental work. From some incidents of the investigation, so far 

 as it has hitherto proceeded, I am disposed to believe that the motion 

 in any plane chemical figure is not along the radius, but at right 

 angles to the radius ; and this supposition will, if verified, explain the 

 repulsion. The existing results afford proof of the following pro- 

 positions, viz. : — (1.) Chemical action can take place at a distance; and 

 (2.) Two or more chemical actions identical except in position, completely 

 exclude one another. 



