560 



substrate, the salts might modify the substrate and make it con- 

 sequently more or less susceptible to be influenced by the ferment. 



The phenomenon to be studied would problaby become more implicate. 



The urease, the ureum decomposing ferment, which is found in 

 soybeans is very tit for such like experiments. 



The experiments were executed as follows : 3 cc of a solution of 

 ureum (l^/^ percent) a definite number of cc of the solution of salt 

 and water to constantly the same volumes (100 cc.) were put in a 

 number of tlasks, as a rule 7. The flasks were placed in a flat-bottomed 

 basin in water of the temperature of the room. After the flasks 

 had been so long in the water till the temperature in each of them 

 had become the same, 3 cc. of the urease-preparation, according to 

 Jansen, was added to them. One minute elapsed between the addition 

 of the ferment to each flask. After 50 to 60 minutes the ammonia 

 that had been formed, was titrated with methyl-orange as indicator, 

 every time with an interval of one minute. Consequently the action 

 was of equal duration in each flask. It appeared at a preliminary 

 experiment that equal results were obtained indeed in flasks of the 

 same composition. 



1. Kations. 



The kations used were K-, Na-, NH-,, Mg-, Ba-, Sr-, Ca -. Of all 

 metals the chlorides were used. 



The following results were obtained: (Vide Tab. on the next page). 



If now we express the above figures graphically in such a way 

 that the salt-concentration is indicated on the abscis, and the quan- 

 tity of ammonia that has been formed on the ordinate, then irregu- 

 larities strike us with two metals viz. calcium and magnesium. 



^\. 1. 



