Voltaic Action in Teeth Fillings. 45 



"Volta found, however, that if into a circuit such as the above 

 he introduced one Hnk composed of a compound substance, such 

 as dilute brine, or sulphuric acid, or copper sulphate, he akvays 

 obtained an electric current. Conductors of this kind, which 

 Volta called conductors of the second class, akvays undergo chemi- 

 cal decomposition when introduced into a circuit containing two 

 different metals, and akvays yield a current. 



"The modern name for a conductor of the second class is elec- 

 trolyte, i. e., any substance which is decomposed when a current 

 passes through it. Conductors of the first class practically include 

 only carbon and the various metals. 



"Definition of a voltaic cell. It has been found by experiment 

 that no two conductors when joined together will produce a cur- 

 rent so long as they are at the same temperature. But the follow- 

 ing combination, suggested by Volta, and named after him, 'the 

 voltaic cell,' will always give a current : The voltaic cell is defined 

 as three or more conductors in series, each conductor being made 

 of a different substance, and not all belonging to the same class." 



It is thus very clear that gold and tin, two conductors of the 

 first class, and saliva, a conductor of the second class, constitute 

 clearly a voltaic cell, and the inevitable result of such a combina- 

 tion is just what takes place in every voltaic cell when two metals 

 are put in contact and both are dipped into an electrolyte — a cur- 

 rent flows and the baser metal is dissolved. 



A number of prominent dentists whose attention has been called 

 tO this matter have assured me that this theory, and my own ex- 

 perience, are confirmed by their own observation. However, there 

 are some who deny voltaic action in combination fillings. I con- 

 sider it of scientific and economic importance that this matter be 

 given wide publicity both among dentists and among the general 

 public, for if there are dentists who insist upon imposing upon 

 their patients in the use of combination fillings, our only defense 

 is to let the public know the facts in the matter so that we may 

 refuse to be imposed upon by such practice. 



It should perhaps be ag-ain emphasized that voltaic action is only 

 to be expected when both metals are left exposed to the saliva. 

 However, as thermo-electric disturbance may be expected with 

 the variations of temperature, as indicated in the above laws, it is 

 my opinion from the standpoint of an electrician, that combina- 

 tion fillings are in no case to be preferred to pure gold. 



