i9o8] 



POND— SOLUTION TENSION AND TOXICITY 



239 



It may be that the zymolyte ethyl acetate tends to minimize the differ- 

 ence in relative toxicity as compared with the zymolyte ethyl butyrate. 

 \MiiIe this is a plausible explanation, it has Uttle value in the absence 

 of con\incing evidence, and we cannot select the determining factor. 

 WTiy the variations in the different tests should be relatively so wide is 

 not understood, especially in view of the precautions to avoid error.' 

 The following test shows that barium is more toxic than lithium under 

 the same conditions as imposed in a contemporaneous test. This 

 emphasizes the apparent tendency of the barium group to exceed the 

 sodium group in toxicity, and such a conclusion is perhaps permissible 

 in view of all the results of this work and that on ethyl but}Tate, but 

 it would certainly be difficult to say how much more toxic. 



TABLE VII: Barium and lithium in contemporaneous test 



BARrCM 



m 



Control 



Enzvrre 



Increase 



Water 



256-.. 

 128... 



64... 



32-. 



16... 



8... 



o. 10 



o 

 o 

 o 

 o 



o 

 o 



09 

 09 



09 



10 

 10 



10 



o. 

 o. 

 o. 

 o. 

 o. 

 o. 

 o. 



16 



12 



10 



O.IO 



0.07 

 0.06 

 0.06 



0.03 



0.02 

 0.00 



LiTHir^r 



64 



32 

 16 



8 



4 



2. 



O.IO 



O.IO 

 O.IO 

 O. TO 

 O.IO 

 O.IO 



a 



o. 

 o. 

 o. 

 o. 

 o. 



O. 



20 



18 



12 



II 

 10 



E 



f 



O.IO 



0.08 



0.07 



0.02 



O.OI 



0.00 



Enzy 



ne 0.05 per cent. Incubation 5 hours at 40^ C. 



In the preceding tests it will be remembered that the salts themseh^es 

 are neutral in all the concentrations used, and that the acidity of the 

 reagent is quite uniformly the same for all the concentrations of a 

 given salt, and that the acidity of the control is the acidity of the 



enzyme solution itself, as is indicated bv the figure 



(( 



Water" in the 



umn 



It is apparent that the highest satiu-ation is required 



9 Possibly the cnzyva^^ solutions differed sufficiently to account for the discrepan- 

 Then too, the insolubility of the zymolyte may have been responsible to some 



