1896 | TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 51 
For the K,Fe(CN), at 18° C. and of ;', gram-molecule 
strength about $3 of the molecules will be broken up, and for 
a1, gram-molecule solution about 33 of the entire number of 
molecules will be split up. For the K,Fe(CN), at 18° C. and of 
gy gram-molecule strength, about }§ of the total number of mole- 
cules will be dissociated."* The solutions used will then contain 
a certain number of undissociated molecules besides the K* 
ions and the Fe (CN); ions. The K* ions have already been 
mentioned as non-poisonous at these dilutions, so the toxic action 
must be referred to the Fe(CN); ions and to some extent to 
the undissociated molecules. 
The much greater strength of solutions which the seedlings 
are able to withstand in the above experiments over that for the 
KCN, show that the CN has lost its toxic action to a great 
extent by combining with the Fe to form the Fe (CN), ion. 
The roots of P. sativum were killed by the ¢7)9 KCN, while 
it took ;4, potassium ferro- or ferri-cyanide. The molecule of 
the potassium ferro- or ferri-cyanides contained six times as much 
cyanogen, hence it required 384 times as much cyanogen 
in the form of the Fe(CN), ion to produce the same effect. 
The roots of Zea Mais were killed by the gy/59 KCN, while 
it took 54, gram-molecule of K,Fe(CN), or K,Fe(CN), 
to produce the same effect, or 192 times as much CN in the 
form of the Fe(CN)> ion. 
10. SItveR NitraTE + 3KCN. 
Some experiments were also performed to test the action of 
AgNO, + KCN upon the growth of the same seedlings as had 
been used before. The results are given below: 
1 gare FEES 
Tz800 25600 51200 102400| 204800 
mol, mol. mol, mol. mol. 
a Rect 
P. sativum ot 24 fite;...§ 3:58" | ge steam oo 25°" 
hate, es ON ew rer 3.5 2.5 4 
Z. Mais ist 24 hrs...) 1.5 3-25 6 8.25 
eG 24 tire. ces 15.88 2 5.25 
“Ostwald, Chemische Energie 739. 
