INTRODUCTION 7 



figures with observed ones is of a greater use and 

 clearness. 



But we can proceed more simply by putting 

 y = log z, i.e. plotting log ^ as a function of t, in 

 which case we get a straight line (the continuous 

 line in Fig. 2), beginning at the point ^/ = log2 = 

 log 100= 2 and cutting the ^f-axis in the point log z 



Fig. 2. 



= 0, i.e. z= 1, and 2-o = bt , i.e. t =2/b (in Fig. 2 

 4=206, 4 li es so f ar to ^ right that it does not 

 appear in the figure). Here the value of b is 

 very simple, namely, b = 2Jt Q , b is the so-called 

 velocity of reaction, it is equal to 2 divided by the 

 time in which the quantity of cane-sugar has sunk 

 to one per cent of its original value. Evidently 

 the shorter the time for decomposing 99 per cent 



