1327 
the black covering had a temperatnre slightly higher (about 0.5°) 
than the other one exposed to light. 
It is well known that broinine is sensitive to sunlight and manj 
phoro bi'oraination processes Itave been stndied. Roloff (Zeit. Phys. 
Chem. (1894) 13, 327) and recently Benrath (Zeit. Phjs. Chem. 
1910, 74 , 115) studied the action of bromine on oxalic acid in 
presence of sunlight and foiind that it proceeded more rapidlj in 
light than in darkness. 
In the present investigation it is shown that not only oxalic acid 
but oxalates and other organic acids as well as their sodintn salts 
also are acted upon bj bromine water more rapidlj in light than 
in darkness. 
The bromine solution was standardised each day jnst before use 
bj adding an excess of potassinm iodide and titrated against Standard 
sodiiim thiosulphate. Alwajs a blank experiment under exactlj sirailar 
conditions was made in order to get the data in darkness. 
In all cases the whole amonnt of the solution was titrated after 
the lapse of the fixed time. The temperatnre of the experiments 
was 30° C. 
Ammonium oxalate and bromine. 
Quality of Light 
1 
Time of 
t-xposure 
Amount of 
bromine 
added in 
grams 
Unchanged 
bromine 
Volume of solution 
a) Sunlight 
8' 
0.15872 
0.00016 
1 25 c.c. ammonium 
Darkness 
8' 
0.15872 
0.00223 
t oxalate and 25 c.c. 
1 bromine water. 
b) Sunlight 
20 ' 
0.31744 
0.00028 
1 25 c.c. — ammonium 
Darkness 
20 ' 
0.31744 
0.00'’25 
t oxalate and 50 c.c. 
1 bromine water. 
c) Diffused light 
9' 
0.15872 
0.00103 
1 25 c.c. — ammonium 
Darkness 
9' 
0.15872 
0-. 00221 
i oxalate and 25 c.c. 
1 bromine water. 
d) Diffused light 
22 ' 
0.31744 
0.00147 
1 25 C.C. ammonium 
Darkness 
22 ' 
0.31744 
0.00321 
i oxalate and 50 c.c. 
) bromine water. 
