102 BOTANICAL GAZETTE [AUGUST 
28. POTASSIUM FERRICYANIDE (K, FeCnaya 
(Begun December 13, 8 P.M.) 
yess sal per Hee egg ee Thai ge Remarks 
_3b0 15,5 18.5™™ alive, boundary 
ren ij.0 * 19.0 “ Wid es 
a0 20.5 “ 26.0 “ “ . 
20.0 “ 20.0 “ “cc ‘“c 
wdo 27.5 ‘“ 41.0 ‘“ “c “ 
ee aes ly 
600 27-5 52.0 
es ee 25.5 “ce 45.0 “ “cc “ 
Table 26 gives the concentration of cyanogen ions that the 
lupines can bear; it is about the same as that for hydrogen ions. 
In potassium ferrocyanide and potassium ferricyanide the irom 
and the cyanogen radical form complex ions’? which, as tables 
27 and 28 show, have the same toxic effect. This is much less, 
however, than in the case where iron exists in the solution a 
ion by itself or where cyanogen ions as such are present in the 
solution. 
Experiments were also performed with a solution of mercufe 
chloride. The detailed results of these have unfortunately beet 7 
mislaid, but the concentration of this solution that the ip : 
can bear was found to be ;54,, gm. equivalent per liter. Me 
curic chloride is a compound that is but slightly dissociated ek 
concentrations at which it is ordinarily used in laboratories; # 
the above mentioned concentration, however, the dissec” 
must have advanced to a considerable degree. 
From a solution of mercuric chloride mercuric oxide can 
precipitated by means of potassium hydroxide. If, howeveh* 
considerable amount of dextrine be first added to the ne 
chloride solution caustic alkali no longer precipitates mercunt 
oxide. erc 
19 ‘ 
These ions are Fe!’ CN, and Fe’'’ CN, respectively. 
