1896 | TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 139 
experiments upon other acids. This fact is to be explained by 
the partial dissociation of the acetic acid. 
It is also interesting to note that after the killing point has 
been found for the Piswm sativum roots it can be worked out by 
proportion for the Zea Mais. ,N,,, the killing point in other 
acids for Pisum, is to ,§,,, the killing point for Zea Mais with 
other acids, as Yeye the killing point of acetic acid for Pisum 
sativum, is to N, the killing point for Zea Mats, that is, 
, 6400: 1600 :: 1600: 4; 
whence + = 400, and a glance at the table will show that the ,%, 
solution was sufficient to kill the roots of Zea Mais seedlings. 
Klemm ™ has shown that more concentrated solutions of the 
organic acids are necessary to produce disorganization than of 
the inorganic acids. This fact then falls in line with the result 
here obtained for the acetic acid. 
4. COPPER SALTs. 
For the copper salts stock solutions which contained ;} 
gram-molecule to the liter were used. Three different copper- 
salts were used, copper sulfate, copper chloride, and copper 
acetate, and the dilutions were made as follows: 
10° of +45 to 200% = yy1;5 mol. 
100° of gylgq to 200° = gzyy mol. 
100° of g7Zy5 to 200% = tyh55 mol. eke. 
PISUM SATIVUM. 
1 
Copper salts. sou l|rssoe| ese00 srzou | Toeso0 
mol, mol. mol. mol, mol. 
CuSO, Ist 24 hours} .... ee o75e 2.5 ™ RS co 
2d 24 hours) .... ak HN TES ge 13.75 “ 
CuCl Ist 24 hours| .... tes O75" 335 eg 
* (2d 24 hours at eae ORE gre 8.25 * 
EMCSHLO,),}324 8 vuws ewes O75" ae 12.75 
2,24 Wee Le ee 3.5 9 
See ee 
ki Experiments were carried out first with the seedlings of 
Ss“ sativum, two seedlings being placed in each of the solu- 
" Jabrbiicher f. wiss, Botanik 28: 658-664. 
