1338 
2 Hg Cl, + (NHJ, C,0, = 2 Hg Cl + 2 CO, + 2 NH, Cl . 
The ahove aiillior lias showii that tlie sensitiveness of Edkk’s 
acliiioaieter niay be increased eiglity (80) limes in absence of oxjgen. 
Moteover, Roi.ofF (Zeit. Ph^ s. Chern. 13, 329 (1894)) bas sliovvn 
that carbon dioxide, which is one of the products of deconiposition 
and consecpienllj alwajs present, largelj increases the sensitiveness 
of the above form of actinometer. 
The lodine-Oxalate actinometer worked out in this investigation 
and which depends on the following reaction in presence of light 
1, + (NHJ,C,0, = 2 CO, + 2 NHJ 
or 
I, + K,C,0, = 2 CO, + 2 KI 
is absolntelj free from the disadvantages of the Eder Actinometer 
as has been proved bj the foregoing tables that neither oxjgen or 
carbon dioxide has anj intlnence on this actinometer. 
Moreover the estimation of iodine bj Standard sodinm thiosnlphate 
is decidedlj simpler and easier than the estimation of raercnrous 
chloride in the Eder Actinometer. Obviouslj the nse of the iodine- 
oxalate actinometer is lo be preferred. 
It has also been fonnd ont that iodine acts more rapidlj in 
presence of light on other organic acids and their sodinm salts than 
in the dark. 
The action of iodine on formates which takes place according to 
the following eq nat ion 
H . COONa + I, = Nal + Hl + CO, 
is qnite rapid as will be shown in the following table 
Sodium formate and iodine. 
. Quality of light 
Time of 
exposure | 
Amount of 
iodine added 
j Unchanged 
i iodine 
1 
Volume of Solution 
a) Sunlight 
15' 
0.0635 
1 
i 0.C0103 
1 40 c.c. Normal Sodium for- 
Darkness 
15' 
Do 
0.C0295 
1 mate and 5 c.c. iodine. 
b) Sunlight 
26' 
Do 
0.00116 
i 20 c.c. Normal formate and 
Darkness 
26' 
Do 
j 0.C0298 
1 5 C.C. iodine. 
c) Diffused light 
40' 
Do 
0.00154 
) 40 c.c. Normal Sodium for- 
f AT 
Darkness 
40' 
Do 
0.00225 
/ /V 
j mate and 5 c.c. iodine. 
d) Diffused light 
85' 
Do 
0.00142 
1 40 c.c. Normal formate and 
Darkness 
85' 
Do 
0.00224 
1 
^ 10 c.c. yq iodine. 
