i9o8] 



POND— SOLUTION TENSION AN P TOXICITY 



250 



been unsuccessful.'-' in \ie\v of the rcalh' large altenlion that has 

 been devoted lo this subject, it seems surj)rising that no generahzation 

 has been satisfactorily established (Hkrg and (iii:s, /. c). The 

 affinity of ions for their charges is such a fundamental jjroperty that we 

 can hardly conceive of a chemical reaction involving solution in which 

 this aflmity or solution-tension, as some lia\ e called it, does not play a 

 part. On the other hand, there is abundant evidence olTered by my 



TABLE XXI: Ethyl acetate 

 Barium, had, copper, and prtassium in conlcniporaiic nis lest 



COPPER 



LEAD 



128. 

 64. 



2. 10 

 4. 20 



2. 10 

 4. 20 



0.00 

 0.00 



BARIUM 



128. 

 64. 



0.12 

 0.12 



o. 27 

 o. 27 



0.15 



c 15 



POTASSIUM 



128. 

 64. 



0.12 

 0.12 



o. 27 

 o. 27 



015 

 015 



Enzyme o. 10 per cent. Incubation 5 hours at 40 C. 



experiments to show that there is no fixed relation between toxicity 

 and solution-tension to the extent that the toxicilv of substances can 

 be exactly estimated from their solution-tension (Pond, /. c. 274). 

 There is difficulty even in agreeing upon a standard of toxicity. The 

 minimum lethal dose measures the fatal toxicity, but is it a standard 

 of toxicity? Does total inhibition measure the toxicity in my own 

 experiments? In Table XIII we see that w/16384 and 7^/32768 of 

 both mercury and silver are inhibiting and equally inhibiting, but for 



'2 The following paper offers a recent and thorough digest of the more important 

 literature of this subject: Berg, Wm. N., The relation between the physiological action 

 of ions and their physico-chemical properties. New York Medical Journal for July 

 20 and July 27, 1907. pp. 42. 



