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CHAPTER XIII 



4. Effect of Temperature. The following empirical equation, due to 

 Urech 14 , connects velocity of inversion and temperature : 



A(T l -T ) 

 GJ C e T T! 



where C and C 1 are the rates of inversion at 7' and T lf e is the base of 

 the natural system of logarithms, and A is a constant, and equal to 12820. 

 Putting the rate of inversion at 25 C.=i, this expression gives the following 

 rates of inversion at the stated temperatures : 



The Effect of Neutral Salts. It was originally shown by Arrhenius 16 

 that the rate of inversion by acids was accelerated by the presence of the 

 halides and nitrates of the alkalies and alkaline earths. The writer 16 has 

 extended his observations, and has found : 



1. In concentration up to 0-02 N at 100 C., the halides and nitrates 

 have an inappreciable effect on the rate of inversion with very dilute acids. 



2. Under similar conditions the sulphates, sulphites, oxalates, and all 

 alkali and alkaline earth salts of weaker acids retard inversion. 



3. In concentration of acid and salt of the normal order, at ordinary 

 temperatures, the halides and nitrates of the alkalies and alkaline earths 

 accelerate the rate of inversion ; the acceleration increases progressively 

 from chloride to bromide, to iodide, the effect of nitrates being similar to 

 that of chlorides. A difference in the base of the salt has very little, if any, 

 effect ; thus, the acceleration due to the sodium chloride is substantially 

 the same as that due to calcium chloride. 



4. Under similar conditions, sulphates, sulphites, oxalates, etc., retard 

 the rate of inversion. 



Effect of Invert Sugar. The action of invert sugar on the inversion of 

 cane sugar is a peculiar subject, some investigators finding that invert sugar 

 of itself caused inversion, and others observing no effect. Geerligs 17 , in 

 investigating the subject, came to the conclusion that invert sugar of itself 

 had no invertive action, but that in the presence of neutral salts, such as 

 chlorides, nitrates and sulphates of the alkalies and alkaline earths, inversion 

 occurred at the temperature of boiling water, owing to a slight hydrolysis 

 of the neutral salt under the influence of the invert sugar. The writer 16 

 in investigating the same subject, failed to obtain any trace of inversion due 

 to the combined influence of invert sugar and neutral salts, when the latter 

 were present in normal concentration. 



Inversion under Acid Salts. Salts of the heavy metals, such as zinc 

 sulphate, also cause the inversion of cane sugar. This has been chiefly 

 studied by Long 18 ; the inversion is ascribed to the partial hydrolysis of the 

 salt, thereby affording free hydrogen ions in solution. 



Inversion under the Influence of Enzymes. Besides chemical inversion 

 under the influence of acids and acid salts, cane sugar is inverted by the 

 action of certain ferments known collectively as enzymes. The enzyme 

 most studied is that secreted by yeast, and known as invertase. The proper- 

 ties of this body were first investigated by O'Sullivan and Thompson 19 , who 



