288 



REPORTS ON THE STATE OF SC1E>^CE. 



acid, of neutral salts and of temperature is the same. The relative 

 facility of hydrolysis of the three sugars is : — 



Milk-sugar 1-0 



Maltose 1-27 



Cane sugar 12400 



a result which is in harmony with the earlier statements. 



, q^ , Noyes and others have also studied the hydrolysis of maltose at 



100° and 110°. They found a considerable amount of reversion to 

 occur, which Sigmund did not mention ; this was also shown to be the case 

 by Armstrong and Caldwell and is in harmony with Wohl's observations 

 {vide Section E 3). 

 , -iq;. The hydrolysis of the glucoside salicin, as measui-ed by Noyes 



and Hall, proceeds at a rate which is of the same order as that 

 of maltose. The velocity constant in this case also is influenced by con- 

 centration of the acid and the salicin in the same way as for cane sugar. 

 I (^, An interesting comparison has more recently been made by E. F. 



Armstrong of the relative rates at which various glucosides and 

 galactosides are hydrolysed. 

 velocities : — 



He gives the following table of inversion 



The hydrolysis of the glucoside amygdalin, which the author is at 

 present investigating, is comparable with that of the methyl glucosides in 

 velocity. 



, q^.. The hydrolysis of tri-saccharides has been discussed by Wogrinz 



from a mathematical standpoint, but no experimental work has 

 hitherto been published on the topic. 



,r,(.^ The hydrolysis of starch by dilute acid under pressure at high 



temperatures has been studied by Rolfe and Defren. 



The interest of these observations on various sugars lies partly in the 

 comparison of the stability of the various sugars, partly in a comparison 

 with the velocity of enzyme hydrolysis (vide Section N) and, lastly, in a 

 comparison of the activities of various acids in the several cases. 



The following table has been compiled from the above-mentioned 

 researches : — 



* By a curious slip the square root of this value, */53-7 x 10 = 732 was given by 

 Ostwald and has been faithfully transmitted by all the text-books. 



