216 Dr. H. E. Roaf. The Liberation of Ions and the [Jan. 10, 



opposite each other and the muscle was stimulated. If there was no definite 

 deflection of the galvanometer, the cross-section of the muscle was considered 

 to be iso-electric. Some other form of electrode was then substituted for one 

 of the calomel electrodes and the muscle was stimulated. In order to 

 avoid any influence of the stimulating current, the direction of the current 

 in the primary coil was reversed and the stimulation was repeated. 



Chlorine Ions. 



The electrode used to replace one of the calomel electrodes was a silver 

 wire coated with silver chloride. The arrangement was 



Ag | AgCl | muscle | Einger solution | HgCl | Hg. 



This arrangement gave an electrical potential which was compensated in the 

 usual way, and from the amount of compensation it was possible to calculate 

 the concentration of chlorine ions in contact with the silver chloride-silver 

 wire. After the compensation was accomplished the muscle was stimulated, 

 and the direction of the galvanometer deflection was noted. The results 

 showed that the silver electrode became more negative than it was with the 

 resting muscle. 



There are two contacts where the potential may be produced; the contact 

 Einger solution-HgCl-Hg not being affected by the contraction of the muscle. 



The first is the contact Ag-AgCl-muscle, and an increase in chlorine ions 

 would produce the increase in negativity when the muscle contracts. 



The second contact is that between muscle and Einger solution, and the 

 potential would depend on the relative ionic mobilities of the positive and 

 negative ions set free. Tor a binary electrolyte the formula would contain 

 the ratio (u — v)/{u + v), where u = the rate of migration of the positive 

 ion, and * = that of the negative ion. A positive ion diffusing away from 

 the muscle more rapidly than the negative ion would cause the mercury 

 electrode to become positive, that is, the silver would become negative. 



The only positive ion that need be considered is the hydrogen ion, as that 

 is the only one that would give an appreciable value for (u — v)/(u + v), and 

 it will be shown in the next section that hydrogen ions are liberated when 

 muscle contracts. 



Against the possibility that when the muscle contracts the negative charge 

 on the silver electrode is due to hydrogen ions diffusing into the Einger 

 solution, it may be pointed out that a saline electrode in contact with the 

 active portion of a muscle becomes negative. Hence there may be a 

 potential opposed to that due to the chlorine ions, and perhaps the action 

 current may be added to the observed potential to give the true potential 



