80 CHEMICAL STATICS 



where A is the initial concentration of the cane-sugar, X is the 

 amount inverted after a time t, and /c is a constant (at constant 

 temperature) which varies directly as the hydrion concentration 

 of the solution. The period during which the reaction proceeded 

 was constant (4 hours) ; hence, if X be the amount of sugar trans- 

 formed after the addition to its solution of a measured volume 

 of HCl-solution, and X' that after the addition to the same con- 

 centration of cane-sugar of the same volume of the HCl-solution, 

 to which, however, protein has been added then: 



C ^ logA-log(A-X) 

 C'~ \ogA-\og{A-X')' 



where C is the concentration of hydrions in the pure acid, and 

 C that in the acid to which protein has been added. Knowing 

 the value of C that of C can be immediately calculated. From 

 his results Cohnheim concluded that 0.25 gram of protalbu- 

 mose, dissolved in 5 cc. of solution containing 0.025 gram of 

 HCl, combines with 4.16 per cent of its own weight of the acid, 

 — similar determinations were made with other albumoses. 



Hardy (16) has employed the catalysis of the inversion of cane 

 sugar by H+ ions in the measurement of the acid-binding capacity 

 of serum-globulin, and that of the saponification of methyl acetate 

 by OH' ions in the measurement of the base-combining capacity 

 of this protein. 



In this connection (although, owing to the complexity of the 

 experimental conditions, they have, as yet, but a qualitative 

 significance) the results obtained by a number of observers (12) 

 (7) (22) (23) (2) (1) (53) (35) on the protection conferred by 

 proteins against the destruction of enzymes by acid or alkali may 

 be mentioned. As is well known, the proteolytic enzymes, for 

 example, are very rapidly destroyed by an excess of free acid 

 or base, the action of the acid or base being, probably, that of 

 catalysing the destruction (hydrolysis?) of the enzyme which 

 occurs even in pure water. If, however, protein be added to 

 acid or alkaline solutions containing these enzymes, the rate of 

 destruction of the enzyme is greatly diminished, and this has 

 been attributed by Falk (12), Langley and Edkins (22), Langley 

 and Eves (23) and Vernon (53) to a binding of the free acid or 

 alkali by the added protein. It must not be forgotten, however, 

 that the proteolytic enzymes are, in the presence of protein, 



