10 LOCALIZED ELECTRIZATION. 



period of from twenty minutes to half an hour. For an examination of the 

 probable influence of friction electricity in the treatment of painful and 

 spasmodic affections consult Dr. Eadcliffe's ' Lectures on Epileptic, Spasmodic, 

 Neuralgic, and Paralytic Disorders of the Nervous System.' — U. T.'\ 



Part II. 



CONTACT ELECTRICITY (GALVANTSM). 



The term dynamic electricity, that is to say, electricity in motion, 

 has been used to denote the electricity produced by contact 

 {galvanism), and the electricity caused by induction. This form, 

 obtained from voltaic piles, or from an electro-magnetic apparatus, 

 possesses physiological and therapeutical properties essentially 

 different from those of static electricity. 



The most important property of dynamic electricity, regarded 

 from a physiological or therapeutical point of view, is that by 

 which its action can be directed to, and limited within, almost any 

 organ of the body. It is shown, indeed, by my experiments, that 

 we may at pleasure confine this agent to the skin, or may cause it 

 to penetrate the skin, without puncture or incision, and may limit 

 its action to the subjacent organs, the nerves, the muscles, or even 

 the bones. Of this I shall give evidence in the sequel. 



The cutaneous sensation produced by dynamic electricity may 

 range from a simple titillation to the most acute pain. The exci- 

 tation thus produced may always, by the use of special means, 

 be confined entirely to the skin, whatever be the power of the 

 current. 



The same electro-dynamic force, directed upon a muscle, or 

 upon a nerve-trunk, has power to produce the most energetic 

 muscular contraction, without any of the general shock that charac- 

 terises the action of static electricity, and that usually forbids its 

 employment. 



Such are the principal effects to be obtained from dynamic elec- 

 tricity, which includes contact electricity {galvanism) and induced 

 electricity. 



But each of these forms of dynamic electricity possesses special 

 properties, physical, chemical, and physiological, such as to prevent 

 them from being employed indifferently in practice. These special 

 properties may even fulfil certain determinate indications, and they 

 therefore require to be separately considered. 



§ I. — Physiological Projoerties. 

 Quantity and tension being equal, every form of electro-motor 



