IX. ELECTROPHORESIS 291 



sleeves (0) with large electrode chambers (Z) that contain silver- 

 silver chloride electrodes {S) which, when surrounded by a potassium 

 chloride solution, will allow the electric current to enter the system 

 without any accompanying polarization of the electrodes and attend- 

 ant evolution of gas. These electrode vessels are filled with a buffer 

 of the same composition as the overlying liquid at the boundaries. 

 This arrangement, and the long path existing between the electrodes 

 and the boundaries in the U tube, will give adequate protection against 

 the possibility that the products of electrolysis that accumulate in the 

 regions of the electrode will ever reach the region of the boundaries. 

 Requirement a is thus adequately fulfilled in this apparatus. 



The cell proper shown in Figure 4 is one employed for analytical 

 purposes and consists of three sections. These sections are contacted 

 through ground glass plates lubricated by a grease that prevents leak- 

 age out of or into the cell (when the instrument is placed in a water 

 bath) and will allow horizontal displacement of parts of the cell with 

 respect to each other. This is necessary in order to obtain a sharp 

 initial boundary between the buffer and the solution containing the 

 material to be analyzed. Mechanical devices (V) are attached to the 

 frame and accomplish this required displacement of the center and 

 bottom portions of the cell when the cell is connected to the electrode 

 vessels through rubber sleeves attached to the static top portion of the 

 cell. 



Filling of the cell may be accomplished as follows: With the cell and 

 electrode vessels assembled in the frame and the glass parts X and Y (Fig. 

 3) removed, protein solution (for example) is introduced into the U tube in 

 an amount sufficient to a little more than fill the bottom part of the U tube. 

 This bottom section is moved to the left, let us say, sufficiently to close the 

 lumen of the U tube. Then the right hand leg of the U tube is filled with 

 protein solution. Next, the left hand leg is washed with buffer and filled 

 with buffer. The center part of the U tube I3 now moved to the right closing 

 the connection of the lumen with the top portion of the cell. Both sides of 

 the top portion are washed with buffer, then filled with buffer together with 

 the electrode vessels. The glass parts X and Y are replaced, the electrodes 

 introduced, and saturated potassium chloride solution is passed into the 

 bottom of the electrode vessels, through the hollow tubes leading down to 

 the electrodes, until the electrodes are surrounded by the potassium chloride 

 solution. The electrode vessels are filled to an even level (top of piece X) 

 with buffer solution and the whole assembly is placed in a constant tempera- 

 ture bath. After the contents have i-eached bath temperature and with the 

 stopcock on part Y closed, the parts of the U tube are brought back into line. 



