276 REPORTS ON THE STATE OF SCIEXCE. 



1 QA9 Ostwald has spoken benignly, although without enthusiasm, of 



this theory of catalysis of Euler's, remarking that it cannot be 

 applied to cases v/here a mixture of two electrolytes produces a greater 

 efl'ect than the sum of their two separate effects. 



E 3. — Miscellaneous Theories of Sugar Inversion. 



,o-„ Dubruufaut maintained that cane sugar partakes of the nature 



of a salt, the glucose being basic. Inversion, according to him, is 

 a purely chemical action of the acid used. 



Spohr, who supported the Clausius-Williamson dissociation hypothesis, 

 CQR appeared to think that the sugar is inverted by nascent radicles 



of H and (OH), the number of which was increased by the presence 

 of an acid. 

 1«j^Q Ostwald,^ on the other hand, expressed the opinion that 'the 



affinity of the acid for the alcoholic hydroxyls of the glucose and 

 levulose produced acts in a predisposing fashion,' hence the presence of 

 acid quickens inversion. This view was published about tlie same time as 

 Arrhenius's theory {vide E 1, above). 



An important contribution to this subject was made by Wohl, 



who advanced a new theory of inversion. Wohl showed that the 

 optical inversion of cane sugar by acids proceeds further if the quantity 

 of acid used be small than if it be great. It was found that the rotation 

 fell to a minimum and then on further heating reverted. The reducing 

 power undergoes a similar change simultaneously. That is to say, a slow 

 secondary change was occurring, whereby the monoses were being coupled 

 again to some biose substances with less reducing power. ^ Wohl 



"o 



In the same year isomaltose was prepared by E. Fischer by the 



up ^ 



showed that under his conditions it was mainly the levulose which 



reverted and he isolated a dextrin which on hydrolysis gave levulose 



again. 



action of hydrogen chloride in excess on glucose in the cold. 

 1 QO-i Wohl's work has also received support from Noyes and his pupils, 



who have investigated the hydrolysis of maltose with dilute acid 

 , p^ , and found that reversion of the glucose occurs. Armstrong and 



Caldwell have, in fact, measured the rate of reversion of glucose 

 and galactose.^ 



Wohl explained the reversion by supposing that the acid combines 

 with the lactonic ring of the monoses, thus : — 



-CH . GH(OH) . CH(OH) . C(OH) .- -CH . CH(OH) . CH(OH) . C(OH)- 



X^ 1 



/ H CI 



the chlorhydrin produced giving a disaccharide on losing hydrogen chloride. 

 In inversion, the hydrogen chloride is supposed to combine with the 



" General Chemutry, Walker's translation, 1889, p. 355. 



' This agrees with Meissl (J. Prakt. Chem., 1882 (2), 25, p. 127) and with 

 Winston (J. Analyt. Chem., 1888, 2, p. 152), who both record the reversion of glucose 

 with dilute HCl at high temperatures. 



» See also E. F. Armstrong, Proc. Roy. Sac, 1905, 76, p. 592. 



