676 



TEMPERATURE AND LATENT PERIOD 



graphically. In Fig. 3 are drawn the isotherms of the reaction 

 Z, — ^ r at the temperatures indicated. In the construction of these 

 isothenns the quantity of L present at the beginning of the latent 

 period is considered to be 1 gram-molecule, and the amount of T 

 necessary to accumulate in the sense organ is put equal to 0.10 gram- 

 molecule. These quantities are chosen arbitrarily for convenience. 

 They may be put at any value without changing the analysis in the 

 slightest degree. The essential point is merely that the amount at 

 the beginning and the amount necessary for the response must be the 

 same at all temperatures. Accepting these quantities and knowing 



TABLE I. 



Velocity Constants of the Latent Period Reaction, L ^> T, at Diferent Temperatures. 



Values above 21° Calculated from the Arrhenius Equation when m = 19,680. 



the time interval during which the 0.10 mol of T is formed, it is a 

 simple matter to calculate the velocity constants (y^i) of the latent 

 period reaction from the equation 



ki 



2.303 



I 



loR 



(4) 



which represents the course of a monomolecular reaction. In equa- 

 tion (4), / is equal to the latent period as given by the heavy line in 

 Fig. 2; a is equal to 1 mol; x is 0.10 mol; and 2.303 converts Briggsian 

 logarithms to the Naperian system. The velocity constants so 

 obtained are given in Table I. 



