Mr. J. Napier on Electrical Endosmose. 17 



in measure ii ounce, did not change the colour of blue litmus 

 paper, nor give any precipitate with nitrate of silver : here 

 also, as in the last experiment, we have muriatic acid being 

 transferred in small quantities from the positive to the inter- 

 vening liquid. But another feature presents itself, the great 

 amount of measurable endosmose and the almost entire 

 absence of electrical decomposition ; at the same time the en- 

 dosmose being principally confined to the two vessels contain- 

 ing water, as if the acid in the cell had only acted the part of 

 an electrode. On reversing the condition of the last expe- 

 riment, the positive and glass vessel being charged with di- 

 stilled water, the negative with the dilute muriatic acid, 9-pair 

 battery, for sixteen hours, the positive vessel lost 1^ ounce; 

 the glass vessel had increased 1£ ounce, while the negative or 

 acid solution underwent no alteration, showing again the en- 

 dosmose only between the two cells containing water. 



Several experiments were repeated both with the single and 

 double cells, having muriatic acid as the positive solution, 

 with sulphate of copper, water and alkalies as the negative so- 

 lution; in some I had transfer of acid in small quantity, in 

 others no indication of transfer ; I believe the cause of dif- 

 ference to be in the texture of the partition ; when a diaphragm 

 was used less porous, the endosmose was considerable, in one 

 case amounting to 4 grains in thirty hours. Nitric and sul- 

 phuric acids, which are much more easily transferred than 

 muriatic acid, have also had their transfer resisted by two 

 closely-textured diaphragms, passing through one into the 

 mid-division but not into the negative solution: however, these 

 results show that all kinds of salts or acids are not transferred 

 with the same facility, probably from their power of conduc- 

 tion. 



While operating with the double cells, having an acid in 

 the positive and water in the middle and negative cells, I have 

 several times observed that both positive and negative solu- 

 tions increased in bulk at the expense of the middle solution ; 

 in one instance the positive solution had gained 1 ounce, the ne- 

 gative gained three-fourths of an ounce, and the middle solution 

 had lostlf ounce. The negative and positive solutions originally 

 contained only 2 ounces, the electrodes measured 2 by 1 inches; 

 nevertheless in these instances the transfer of the acid from 

 the positive to the negative was considerable. The different 

 acids gave different results of this sort; with sulphuric acid 

 the increase was greatest, muriatic acid one-half less, nitric 

 acid about one-fourth of the sulphuric ; whether this be the 

 result of any fixed law I cannot say, the times I have ob- 



Phil. Mag. S. 3. Vol. 29. No. 191. July 1 846. C 



