on Molecular Arrangement. 3 



centre; ami these are crossed by small streamers springing 

 laterally from these primary curves, presenting an appearance 

 similar to that shown in fig. 3. These curves are constantly 

 varying in position, but they uniformly preserve the utmost 

 regularity. 



5. The magnet was suspended from a tripod, and two steel 

 needles attached to its poles; these needles were made to dip 

 into a solution of nitrate of silver in a watch-glass. As the 

 pellicle formed over the surface, it arranged itself in a series 

 of curved lines, as represented in fig. 4, which are strikingly 

 similar to those produced by sprinkling iron-filing on 

 stretched paper placed over a magnet. That these curves 

 are due to magnetic influence there can be no doubt, as no 

 such effect could be produced by any cooling influence, inde- 

 pendent of magnetic excitation. 



6. A similar arrangement was allowed to remain in action 

 for twelve hours. At the end of this time crystallization had 

 taken place in every part of the fluid, but there was an evi- 

 dent tendency to a curvilinear arrangement of the crystals. 

 Around the wire depending from the north pole of the mag- 

 net, some revived silver had made its appearance : no such 

 change was discovered at the south pole. 



7. Wires similarly suspended were dipped into a solution 

 of sulphate of iron. Crystallization commenced around the 

 wire at the north pole, but after a few hours crystals had 

 formed around both of the wires, but in the greatest quantity 

 around the north pole wire. On removing them from the so- 

 lution, the crystals were found to present an arrangement si- 

 milar to that represented in fig. 5, showing obviously a ten- 

 dency to arrange themselves along lines of magnetic direc- 

 tion. 



8. A solution of protonitrate of mercury was placed under 

 similar circumstances; crystallization commenced at the wire 

 suspended from the north pole, and proceeded rapidly to a 

 line midway between the two wires; one-half of the fluid being 

 crystallized and the other remaining fluid. At length a few 

 crystals formed around the wire hanging from the south pole, 

 which all took a direction towards the opposite arrangement 

 of crystals. 



9. With a more dilute solution, the crystallization of the ni- 

 trate of mercury took place only around the wire at the north 

 pole, and immediately at the central point between the two 

 wires, from which small needle-shaped crystals radiated to- 

 waids either pole. 



10. A plate of glass, with an edge of clay, forming a shal- 

 low trough, was placed upon the poles of an electro-magnet, 



B2 



