July io, 191 3] 



NATURE 



479 



by electric currents is a chemical treatment, and its 

 chemical actions must explain the results obtained. 

 The stimulation of nerve and muscle is a 

 chemical stimulation by displacement of ions. 

 Nernst, in fact, has expressed the formula for 

 nerve excitation in terms of ions. The sensation 

 telt in the skin during the passage of a current 

 is a chemical effect, and by altering the composi- 

 tion of the saline solution with which the elec- 

 trodes are moistened, its character can be altered 

 so that the sensory effects become more notice- 

 able either at the negative or at the -positive elec- 

 trode. With sodium carbonate it is the negative 

 electrode (ions of CO a ) which gives the greatest 

 sensation. With sodium chloride it is the posi- 

 tive electrode (sodium ions), and so on in great 

 variety. 



Thus a practical lesson may at once be drawn 

 from a knowledge of ionic effects, namely, that 

 a solution of sodium carbonate should not be used 

 for moistening the electrodes in electro-diagnosis, 

 because in that procedure a small negative elec- 

 trode is used with high concentration of current, 

 and in these circumstances the presence of a car- 

 bonate in the liquid causes unnecessary pain to 

 the patient. Again, in using chlorine ions for the 

 softening of scar-tissue it saves the patient some 

 discomfort and facilitates the toleration of massive 

 currents to use the chloride of ammonium at the 

 anode in preference to that of sodium, because 

 the ammonium ion affects the sensory nerves of 

 the skin in a less degree than the ion of sodium. 

 There is another direction in which the applica- 

 tion of the principles of ionic movement has in- 

 creased the therapeutic powers of electrical applica- 

 tions, and that is in the direction of treatment by 

 larger currents. If we look in the text-books of 

 electro-therapeutics we see continually that 

 currents of 5 or 10 milliamperes are prescribed. 

 Formerly that was as much as could be given 

 without causing discomfort or producing super- 

 ficial burns. The metal-plate electrodesand the 

 small buttons or discs covered with a thin layer 

 of chamois leather and set in handles and applied 

 to the affected region did not permit the use of 

 large currents ; Leduc has told us why this is the 

 case. With such electrodes the ions of hydrogen 

 and hydroxyl which are formed at the metallic 

 surfaces can quickly reach the skin surface. They 

 are strongly caustic and tend to produce pain 

 and burns, and this can be obviated by the use 

 of electrodes composed of thick, folded cloths 

 over which is laid a metal electrode faced with 

 two or three layers of thick felt. The whole is 

 moistened with appropriate saline solutions and 

 bandaged to the patient, who thus can tolerate 

 applications of 50 milliamperes or more, and that 

 for times of fifteen or twenty minutes or longer 

 without any burning or blistering of the skin. 



It is not surprising that this change of method 

 brings results which are superior to those of the 

 past. Indeed, if the theory of ions in medical 

 electricity had done nothing else of value, it would 

 deserve all praise for having taught us how to 

 use larger currents. Take, for instance, the treat- 

 NO. 2280, VOL. 91] 



ment of paralysed muscles. A distinguished 

 French writer has recently told us that he has 

 gradually increased the duration of his electrical 

 applications in such conditions to periods of one 

 hour twice daily, and uses rhythmic currents which 

 are not less than 25 milliamperes, and that in the 

 infantile paralysis of children the little patient is 

 so slightly inconvenienced by these applications 

 as to play and even to sleep while they are proceed- 

 ing ; also that the results of such intensive treat- 

 ment are entirely good, and produce not the least 

 sign of fatigue or exhaustion. 



The ionic theory of electrical treatment which 

 has shown us how to use large currents has also 

 shown the necessity for them. If the results to 

 be gained are produced by the chemical inter- 

 change set up in a tissue, it is manifest that to 

 obtain them one must use a strength of current 

 which is capable of producing a distinct effect; 

 and for the same reason the time of an applica- 

 tion must be lengthened. The chemical changes 

 caused by a current of 50 milliamperes for twenty 

 minutes are ten times greater than those given 

 by 10 milliamperes for ten minutes, and are 

 therefore ten times more likely to produce an 

 appreciable effect. The results of adopting this 

 view and of increasing the quantity of current em- 

 ployed may make all the difference between success 

 and failure. It is thus that the treatment of 

 neuralgias can be made effective, and the same 

 occurs in the treatment of many affections of 

 the joint structures. 



In the ionic theory of electrical treatment we 

 have to consider two factors — the chemical inter- 

 changes set up within the tissues and the intro- 

 duction of ions from without. The second of 

 these considerations has added notably to the 

 scope of electrical treatment. In the treatment 

 of superficial morbid states there can be no doubt 

 of the actual penetration of the external ions into 

 the part treated; and the use of the zinc ion 

 introduced at the positive pole from material 

 moistened with a solution of a zinc salt has led 

 to the successful treatment by electrical means of 

 a whole series of superficial ulcerative conditions 

 of the skin and the various orifices of the body. 



In the treatment of affections of the deeper 

 tissues the method of the introduction of ion* 

 from pads moistened with appropriate solutions 

 has also achieved many successes, notably in 

 conditions of so-called neuralgia, states which are 

 almost always due to neuritis or perineuritis — for 

 example, in many severe neuralgias of the tri- 

 ereminal nerve. Quinine and salicylic acid, the 

 latter especially, are useful in these conditions 

 when introduced by the electric current. 



In chronic gouty conditions the introduction of 

 the salicylic ion is also of great value. Iodine 

 ions and lithium ions to a lesser extent also seem 

 to be useful in gouty conditions. The chlorine 

 ion, recommended by Leduc for its softening 

 action upon scar-tissue, has proved itself valuable. 

 Leaving the chemical effects of electrical 

 currents, let us turn to the consideration of the 

 thermal effects. The use of electricity for thermal 



