282 REPORTS ON THE STATE OF SCIENCE. 



■joQj^ Bordt, however, showed that inversion is slower in presence 



of moderately large amounts of glycerol. 



At high temperatures (100°) glucose is said to act as an acid and 

 1898 ^-0 promote inversion in cane-sugar solutions. Thus Geerlings found 



that a mixture of glucose and a neutral salt could cause inversion 

 at high temperatures and he attributed this action to the partial libera- 

 ,gQg tion of HCl from the KOI by the acidity of the sugar. W, A. 



Smith has confirmed this result. The explanation offered, in- 

 volving an assumption of acidity on the part of glucose, seems to be open 

 to doubt when it is remembered how easily the carbohydrates are oxidised 

 189S ^^ ^^^^ products under these conditions. Kullgren, however, arrived 



at the same conclusion on finding that various sugars retard 

 iQQQ the hydrolysis of ethyl acetate by NaOH. Cohen has measured 



the extent of this retardation for various sugars and has found 

 that mannitol has very little effect in comparison with the others. 

 Hence Cohen, too, adopts the idea that the sugars are acidic. He 

 promised to discuss the problem mathematically, but the paper has not 

 yet appeared. 



1901_ Lippmann cannot admit that the sugars are acid in nature. 



1904 Mellor and Bradshaw have noted that the addition of glucose 



and fructose beforehand, although it affects the absolute value of 

 the velocity, does not impair the constancy of the value of K in any 

 one experiment. 

 •tnn-t Henri and des Bancels claimed to have established that the 



simultaneous catalysis of methyl acetate in the same solution does 

 not appreciably affect the rate of inversion of cane sugar at 29°, whilst 

 the hydrolysis of the ester itself is somewhat faster in presence of sugar. 

 ■|qQ, A far more comprehensive research on the same subject was 



published simultaneously by Coppadoro, It was shown by the 

 latter that Henri and des Bancels' result was only valid for volume- 

 normal solutions containing a large proportion of acid (- HCl). When, 



however, dilute acid is used (,„_ and ^ j, the hydi'olysis of the cane 



sugar is considerably retarded by the methyl acetate, but the hydrolysis 

 of the ester is itself much accelerated. This acceleration, however, is 

 merely due to the displacement of water by the sugar in the volume- 

 normal solutions used. Coppadoro showed that in weight-normal solu- 

 tions the presence of cane sugar has not the slightest effect on the 

 hydrylosis of methyl acetate. [Hence the viscosity of the sugar has little 

 effect on the rate of catalysis of methyl acetate and it follows that 

 Kullgren's result (see above) is probably due to the formation of sucrates.] 



Methyl acetate may be supposed to act in the same way as alcohol (see 

 below, H 2) in retarding the inversion of sugar. There is thus no support 

 for the separation of acid catalysis from enzyme action in Henri and des 

 Bancels' classitication. 



A complete discussion of the modus operandi of neutral substances, 

 jQQg hitherto considered in a very superficial manner, has recently been 

 published by the author. It is obvious that we must take into 

 account (1) retardation by mechanical hindrance ; (2) acceleration by 

 combination of the added substance with water of hydration, thus con- 

 centrating the solution ; (3) combination with the hydrolytic agent, thus 



