Chemical Science. 169 



corresponding to the boreal pole of the needle, was first immersed, 

 the austral pole went to the west. When in place of muriatic acid, a 

 solution of ammonia, mineral alkali (soda), or sal-ammonia, was 

 used, the results were exactly the same ; but if a solution of vegetable 

 alkal'i (potash) was used, the deviations were all in the opposite 

 directions. Pure water produced no effect but ^fo of acid made it 

 active. All solutions of salts, or acid, thus applied, produced an 

 effect on the needle. It appears in these cases that, according as 

 the first contact is made to the right or left, an arrangement of 

 molecules is established in the fluid, proper to form a species of pile 

 of which the two poles are very distinct, and that the whole of this 

 little pile is reconstructed in the opposite direction, when the contact 

 is made in the opposite way. 



Place the needle over the condenser, the wires of the latter and 

 the needle being parallel to the magnetic meridian, hold a cylinder of 

 zinc in perfect contact with each end of the wire of the condenser, 

 ihe arrangement will then be zinc, brass, zinc ; plunge the cylinder 

 corresponding with the austral pole of the needle into muriatic acid, 

 and then plunge the other into the same acid, the austral pole of the 

 needle will go towards the east. Repeat the experiment with nitric 

 acid and fresh cylinders of zinc; now the austral pole of the needle 

 will go towards the west. These and other results are the same, 

 whether the conductors are put in contact with the metals before or 

 after their immersion in the fluid. 



The needle condenser and metal bars (zinc), being as before, let 

 the glass be filled with a solution of potash, then immerse the end of 

 the bar corresponding to the austral pole of the needle, and after- 

 wards the other bar, the austral pole will deviate to the east. Take 

 the bars out of the solution, but without changing their position 

 in the hands, and as soon as the needle is at rest, introduce them 

 a«ain, beginning with the bar corresponding to the boreal pole of 

 the needle; the needle (the austral pole) will now deviate to the 

 west. Take the bars out of the fluid, and, without changing them 

 from hand to hand, turn them, so that the ends which were before 

 immersed in the liquid, shall now be in contact with the extre- 

 mities of the condenser wire, then repeat the above experiments, 

 and the same results will be obtained. Finally, if the bars, being 

 well cleaned, are changed from hand to hand, and the experiments 

 again repeated, the same results will be produced. 

 °But now, preserving the apparatus as it was, change the solution 

 of potash for very pure muriatic acid. The zinc bar, corresponding 

 to the boreal pole, being first immersed in the acid, the austral pole 

 will go eastward. Remove that bar from the acid which was last 

 plunged in, and a little while after, the other bar, and without 

 changing them at all in the hand, wait till the needle is quiet; com- 

 mence by the bar corresponding to the boreal pole ; at the moment 

 when that which agrees with the austral pole" shall touch the acid 

 the needle (the austral pole) will deviate towards the west , and 



