56 GENERAL AND PHYSICO-CHEMICAL. 



velocity for every moment is proportional to the concentration of the 

 body decomposed, which is shown by the velocity coefficient in the same 

 experiment being constant at different times. 



2. The velocity coefficient or the reaction velocity with constant 

 concentration of substrate is proportional to the quantity of catalyst. 



The first law has been shown for certain enzymes in case an excess 

 of enzyme is present, namely for saccharase, 1 lactase 2 and trj^psin. 3 It 

 was found that the decomposition in a certain time was proportional to 

 the substrate. In other cases the determination of the correctness of 

 the law was accomplished with difficulty. A part of the enzyme may 

 during an experiment be either destroyed or in other ways (combining 

 with the product) be put out of action; then reverse reactions may take 

 place (page 11) and finally in many cases our analytical methods are 

 incapable of obtaining comparative results for different decompositions, 

 as the reaction in many cases takes place step by step, or several reac- 

 tions occur at the same time. 4 Only in a few cases with especially 

 simple reactions have constant values been found for the velocity 

 coefficient at the beginning, as long as the quantity of reaction product 

 was small and the active quantity of enzyme remained unchanged 

 according to the formula (see page II). 5 



Recently HUDSON 6 has found constant values for k for the entire 

 process of inversion of cane-sugar by saccharase in a faintly acid reac- 

 tion. The reason for the different results of earlier investigators 7 is 

 due, in part, according to HUDSON, to the fact that the multirotation 

 of the glucose formed was not considered by these experimenters before 

 the extent of inversion was determined polariscopically. In the cleavage 

 of salicin by emulsin HUDSON and PAINE 8 obtained constant values 

 for k in the entire process. 



1 Brown, Proc. Chem. Soc., 18, 14 (1902). 

 * Armstrong, Proc. Roy. Soc., 73, 500 (1904). 



3 Hedin, Journ. of Physiol., 32, 475 (1905). 



4 Hedin, Zeitschr. f. physiol. Chem., 57, 468 (1908). 



6 Senter, Zeitschr. f. physik. Chem., 44, 257 (1903); Issajew, ibid., 42, 102; 44, 

 546; Euler, Hofmeister's Beitrage, 7, 1 (1906); Dietz, Zeitschr. f. physiol. Chem., 

 52, 301 (1907); Taylor, Journ. of biol. Chem., 2, 93 (1906); Nicloux, Compt. rend. 

 soc. biol., 56, 840 (1904); Rona, Bioch. Zeitschr., 33, 413 (1911); 39, 21 (1912); Euler, 

 Zeitschr. f. physiol. Chem., 51, 213 (1907). 



6 Journ. Amer. Chem. Soc., 30, 1160, 1564 (1908). 



7 See Henri, Zeitschr. f. physik. Chem., 39, 194 (1901) also A. J. Brown, Trans. 

 Chem. Soc., 81, 373 (1902). 



8 Journ. Amer. Chem. Soc., 31, 1242 (1909). 



