( 455 ) 



sition takes place, the extent of which I will try to determine. 



Some preliminary experiments had also shown that temperatures 

 from 50° to 70° lend themselves very well to the determination of 

 the reaction velocity. In carrying but the experiments, a weighed 

 quantity of the salt was dissolved in previously heated water, so 

 that on introducing the solution into the thermostat, the temperature 

 equilibrium was soon reached. At definite times an aliquot part of 

 the liquid was taken fi-om the bottle by means of a pipette, at once 

 strongly cooled and after diluting if necessary to about l"/o, it was 

 compared colorimetrically with the standard liquid. As such the 

 liquid which was taken from the bottle the first time, namely on 

 commensing the measurement, was used. Special experiments had 

 shown that at the ordinary temperature the transformation proceeds 

 80 slowly that it is not measurable within 24 hours. 



The experiment was generally continued until 30 to 40 Vo of the 

 salt had been converted; at 60° this was the case after IVa to 2 

 hours. 



It has now appeared that the velocity of decomposition of isonitroso- 

 acetophenonsodium is represented by the equation of the first order; 

 it is nnimolecular, since the reaction constant is independent of the 

 concentration. In the case of a 1% solution at 53.^6 k was found 

 to be 0.00062, for a 57„ solution /.• = 0.00059 (time in minutes).') 

 The increase of the reaction velocity with the temperature was shown 

 by the following figures: !"/„ soMion at 60°.l /i-=: 0.0023; at 70° 

 A- = 0.0048') 



The influence of a salt with a common ion and that of free alkali 

 is peculiar. That addition of NaCl diminishes the electrolytic disso- 

 ciation of the sodium salt, was to be expected and may be readily 

 proved colorimelricall}', the addition of 1 mol. of NaCl and 1 mol. 

 of NaOH (or 1 mol. KCN) increases the colour of a 17o solution 

 in the proportion of 93 to 100, that of 10 mols. of NaOH in the 

 proportion of 81 to 100. 



NaCl and NaOH exert, however, also a retarding influence on 

 the reaction velocity. For a 17o solution and 1 mol. of NaCl 

 ^■ = 0.0015; V,„ moi. NaOH, y(;z= 0.0014; 1 mol. NaOH ^- == 0.0015 

 whilst for pure water k = 0.0023. In another experiment, when the 

 transformation had to some extent taken place in pure water, V« mol. 

 of NaOH was added to the liquid and k then fell from 0.0022 to 



^) With solutions of a greater concentration the colour after some time gets 

 more pronounced evidently by polymerisation of the HCN formed. 



') 0.8% sol. at GO', k — 0.0045. The temperature coeff. seems to decrease with 

 increasing temp. ; this requires further investigation. 



