992 
Studies on Enzyme Action. VII.—The Synthetic Action of Acids 
contrasted with that of Enzymes. Synthesis of Maltose and 
LIsomaltose. 
By Epwarp FRANKLAND ARMSTRONG, Ph.D., D.Sc., Salters’ Company’s 
Research Fellow, Chemical Department, City and Guilds of London 
Institute, Central Technical College. 
(Communicated by Professor H. E. Armstrong, F.R.S. Received July 29, 1905.) 
[International Catalogue of Scientific Literature. 
Author’s title slip :—D. Q. 
Subject slips :— 
D 1810 Glucose, condensation of. 
D 1820 Maltose and Isomaltose. Synthesis of 
D 7090 Condensation of Glucose. 
D 8012 Enzymes. Synthetic action of 
Q 1230 Enzymes. Synthetic action of 
Q 1416 Maltose and Isomaltose. Synthesis of, by Acids and Enzymes.] 
The belief has grown up of late years that the enzymes which are capable 
of inducing the hydrolysis of disaccharides or bioses act reversibly ; as yet, 
however, but little has been done to define the theory of the process and no 
understanding has been arrived at as to the limitations to which such changes 
are subject. The same istrue of the action of acids, which also act reversibly 
under certain conditions. 
Croft Hill,* whose observations gave rise to the conception of reversible 
enzyme action, at first thought that maltose alone was produced by the action 
of the enzyme maltase on glucose. Emmerling,f who repeated Croft Hill’s 
experiments, came to the conclusion that the product was isomaltose, the 
biose which E. Fischerf obtained by subjecting glucose to the action of 
concentrated chlorhydric acid. In a later communication,§ while still 
claiming that maltose is formed in small quantity, Croft Hill has admitted 
that the chief product is an isomeride of maltose; but he regards this as 
different from isomaltose and therefore terms it revertose. 
By subjecting a mixture of galactose and glucose such as is obtained by 
hydrolysing milk sugar with lactase to the action of this enzyme, a 
disaccharide, isolactose,|| is formed, which is undoubtedly isomeric with milk 
* “Chem. Soc. Trans.,’ 1898, p. 634; ‘ Ber.,’ 1901, vol. 34, p. 1380. 
t ‘Ber.,’ 1901, vol. 34, pp. 600 and 2206. 
t ‘Ber.,’ 1890, vol. 23, p. 3687 ; 1895, vol. 28, p. 3024. 
§ ‘Chem. Soc. Trans.,’ 1903, p. 578. 
|| E. Fischer and E. F. Armstrong, ‘ Ber.,’ 1902, vol. 35, p. 3151. 
