16 Mr. J. Napier on Electrical Eiidosmose. 



place. Two copper electrodes were used, and the current 

 continued until the negative solution was exhausted of copper. 

 When this was completed the negative electrode had gained 

 in weight 25*1 grains: the solution had increased in measure 

 half an ounce. On testing this by nitrate of silver, only a 

 slight milkiness was obtained. The positive solution was deep 

 blue at bottom, but only a slight tinge above the bottom of 

 the porous vessel ; the positive electrode was coated nearly to 

 one-sixteenth of an inch with a white pasty matter, a great 

 portion had also fallen to the bottom of the vessel : the elec- 

 trode had lost in weight 132 grains. Here we have mea- 

 surable endosmose amounting to half an ounce without any 

 transfer of the acid in solution. 



I now took two porous vessels, the one charged with 2^ 

 ounces by measure of a solution of sulphate of copper, the 

 other with dilute muriatic acid ; these were placed in a glass 

 vessel filled with a measured quantity of distilled water, the 

 cells placed 1 inch apart ; two copper electrodes were used : 

 the muriatic acid cell made the positive solution, the sulphate 

 of copper the negative. A current from 9 pairs was kept up for 

 eighteen hours. At first the decomposition was exceedingly 

 slow, but it afterwards increased ; the results of this experi- 

 ment were — 



Positive solution lost three-eighths of an ounce, pole covered 

 with white powder, and had lost in weight 37 grains; solu- 

 tion contained sulphate of copper. The solution in the glass 

 vessel was tinged blue by sulphate of copper, had lost in mea- 

 sure 1 \ ounce, and gave a copious precipitate with nitrate of 

 silver, showing a transfer of muriatic acid from the positive 

 cell. 



The negative cell had increased in measurel jounce. Nitrate 

 of silver gave no indication of muriatic acid, the electrode had 

 increased in weight 26 grains. 



A similar experiment was again repeated, the negative cell 

 and glass vessel being both charged with distilled water, the 

 positive with dilute muriatic acid ; platinum electrodes were 

 used. A 9-pair battery was attached for sixteen hours. The 

 current passing was sufficient to keep deflected a galvano- 

 meter needle, but no evolution of gas was observed till nearly 

 the end of the experiment, when the poles became covered 

 with small bubbles of gas not large enough to be evolved. 

 The results of this experiment were, positive cell lost in mea- 

 sure one-eighth of an ounce. The solution in the glass vessel 

 was slightly acid, giving a precipitate with nitrate ol silver, and 

 had lost in measure \\ ounce. The negative cell had increased 



