( 72 ) 



P=aR + ^ (1) 



in which R represents the galvanic resistance of the circuit and a 

 and b two constants. 



This formula was likewise applicable to the condensator-experi- 

 ments formerly made bv Dubois (4) of Bern and appeared afterwards 

 to hold likewise for the numerous condensator-experinients made by 

 Weiss, Hermann (5) and others on all sorts of different organs. Espe- 

 cially Hermann's extensive and exact investigation has confirmed the 

 correctness of formula (1). If only the ex[»eriments with large con- 

 densators are excluded, the agreement is very evident though Hermann 

 himself, in a later essay, still continues to deny it. 



The graphical representation of this formula is a hyperbolic curve, 

 which, for very small values of C, mounts vei-y high, and, for very 

 great values of C gradually approaches a straight line parallel with 

 the axis. 



By means of this formula we can calculate the quantity of elec- 



tricit}' Q^CP that is required for a minimal contraction and find 



then, that for decreasing values of C', this quantity regularly decreases: 



the graphical representation of Q is a straight line. For the electric 



energy E^bCP- we tiiid figures that reach, for a definite value 



of C, a minimal \alue, for which consefpiently the organ is most 



sensible. 



F . h 



As /=-, the formula fl) can also be written: i=za-\ , and 



R CR 



as CR represents the time-constant t of the condensator, it becomes 



h 



i = a -^r - (-) 



t 



in which form it is at present much applied by La Picque and 

 his pupils. 



La Picque (6) writes the formula also often thus: 



^=''('"9 *'* 



and calls then ,? the r/u'obase and t the chronaxle of the preparation. 

 All these experiments of La Picque and his pupils prove again the 

 correctness of formula (1) 



If one multiplies formula (1) by C, it becomes 



CP^aCR^b 



and as CP represents the quantity of electricity Q and CR the time 

 constant t of the condensator, the formula assumes the following form 



