1100 
the black covering had a temperature slightly higher (about 0.5°) 
than the other one exposed to light. 
It is well known that bromine is sensitive to sunlight and many 
photo bromination processes have been studied. Rororr (Zeit. Phys. 
Chem. (1894) 18, 327) and recently Benratn (Zeit. Phys. Chem. 
1910, 74, 115) studied the action of bromine on oxalic acid in 
presence of sunlight and found that it proceeded more rapidly 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 sodium salts 
also are acted upon by bromine water more rapidly in light than 
in darkness. 
The bromine solution was standardised each day just before use 
by adding an excess of potassium iodide and titrated against standard 
sodium thiosulphate. Always a blank experiment under exactly similar 
conditions was made in order to get the data in darkness. 
In all cases the whole amount of the solution was titrated after 
the lapse of the fixed time. The temperature of the experiments 
was 30° C. 
Ammonium oxalate and bromine. 
Amount of | 
: : Time of bromine | Unchanged : 
Quality of Light exposure | added in | Bromine Volume of solution 
grams 
ee. | | 
a) Sunlight 8’ | 0.15872 | 0.00016 | 2 N E 
| ORGICE 5 ammonium 
oxalate and 25 c.c. 
Darkness 8 | 0.15872 0.00223. |} bromine water. 
b) Sunlight 20/ 0.31744 0.00028 | N 5 
2oRC:C: 5 ammonium 
. ( oxalate and 50 c.c. 
Darkness 20’ | 0.31744 0.00325 bromine water. 
€) Diffused light 9 | 0.15872 | 0.00103 
DOGG: = ammonium 
| 
| 
| 
| oxalate and 25 c.c. 
Darkness 9’ 0.15872 0.00221 bromine water. 
d) Diffused light 22’ 0.31744 0.00147 N 4 
25) CiC: 5 ammonium 
oxalate and 50 c.c. 
Darkness 22’ 0.31744 0.00321 bromine water. 
