Mr. J. Napier on Electrical Endosmose. 21 



in forty-eight hours the zinc cell had lost three-quarters of an 

 ounce, the platinum cell had gained half an ounce. This 

 experiment was repeated many times with similar results. 



Two large cells were filled with distilled water, and a piece 

 of zinc, measuring 4 by 6 inches, carefully weighed was put 

 into one division and a piece of copper of the same size was 

 put into the other division, the current passed through a deli- 

 cate galvanometer, which kept deflected about 3° ; the posi- 

 tive solution was kept at a given height, the negative was 

 taken out as it increased, keeping the two solutions as nearly 

 level as possible; this was kept up for forty days, when there 

 was found to have passed through from the positive to the 

 negative a bulk equal to 32 ounces, allowing for the evapo- 

 ration, which was known by a similar vessel placed alongside. 

 The zinc was covered with a gray film and had increased in 

 weight 12 grains; this being carefully dissolved off by am- 

 monia, water and the zinc again weighed, it was found to have 

 lost 36 grains, which we may take as the amount of oxidation 

 during the experiment. 



The general conclusions which may be drawn from these 

 experiments respecting endosmose are, 



(1.) That the current of positive electricity passing through 

 a liquid is always accompanied with a current of the liquid in 

 the same direction. 



(2.) If the liquid contains a salt or an acid that is under- 

 going decomposition, the endosmotic current is principally, if 

 not wholly, confined to that salt or acid, unaccompanied with 

 water, and therefore adds little or nothing to the bulk of the 

 liquid into which it passes. 



(3.) When the quantity of electricity which a battery is ca- 

 pable of giving off is greater than the salt or acid can conduct, 

 the extra quantity, if we may so term it, passes through the 

 water, taking with it, and thus inducing a flow of that liquid, 

 into the negative cell, increasing the quantity ; the same effect 

 being produced with water when no salt or acid is in solution : 

 hence the well-known fact, that endosmose is greatest with 

 pure water, and even with currents that give no apparent de- 

 composition, or rather a decomposition so minute as to be un- 

 observed. 



