COHESION AND CRYSTALLIZATION 



79 



the drop becoming more and more black. 

 becomes segmented into granules. 

 which gradually increase in size, and 

 approach nearer to one another and 

 to the centre of the drop, until it 

 assumes the mulberry appearance shown 

 in the photograph (Fig. 19). 



If we sow a number of drops of 

 Indian ink in regular order on the 

 surface of a salt solution, we obtain 

 most beautiful patterns formed by the 

 mutual repulsion of the drops. Figs. 

 20, 21, and 22 represent the successive 

 aspects of seven drops of Indian ink 

 thus sown on a layer of salt solution, 

 and kept undisturbed long enough to 



Each line of force 



Fig. 1 9. — Muri form cohesion 

 figure formed by a drop 

 of Indian ink in a solution 

 of sail. 



How of their evolution. 



Fig. 20. — Seven similar drops of Indian ink diffusing in a salt solution. 

 Two minutes after introducing the drops. 



Fig. 20 shows the aspect after two minutes, when the diffusion 

 is almost complete. In Fig. 21, photographed after fifteen 



