1358 
4) lü c.c. — malonic acid and 5 c.c. — sodium selenite, selenium 
5 5 
separates after 140' ininutes’ . exposure to sunlight. 
N . M 
5) 10 c.c, — Malie acid and 5 c.c. — sodium selenite, selenium 
5 5 
separates after 660' minutes’ exposure to sunlight. 
Here al ‘^0 it has been shown that oxidizing agents (e.g. K Mn 0^, 
Na S, 0„ H, O, etc.) markedly accelerate these reactions. Hence light 
and oxidizing agents plaj the same role of positive catalyst in these 
reductions of sodium selenite. 
Moreover, it has been observed that the oxidizing action of pot- 
assium permanganate on oxalic acid, tartaric acid, cilric acid, malonic 
acid, malie acid, lactic acid, etc. is markedlj accelerated by light. 
A. Potassium permanganate and oxalic acid. 
At 30°. 
N N 
1) 20 c.c. — oxalic acid and 5 c.c. — - KMnO^. Mixture becomes 
colourless i.e. KMnO^ completely disappears after 
Sunlight Diffused light Darkness 
2'— 30" 3'— 50" 8'— 40" 
N N ^ 
2) 20 c.c. — oxalic acid and 10 c.c. — KMnO. 
^10 10 ' 
3'— 20" 
5'— 30" 
12—25". 
B. Permanganate and Tartaric acid. 
N N 
1) 10 c.c. — tartaric acid and 5 c.c. — KMnO, becomes colour- 
5 10 
less after 
Sunlight 
4'— 30" 
Ditfused light 
5'— 50" 
N 
Darkness 
8 ' 
Then to the clear mixture 5 c.c. — KMnO^ was added in each 
10 ' 
bottle ; becomes colourless after 
Sunlight Diffused light 
2'— 30" 3'— 50" 
Darkness 
5'— 45. 
^ N N 
2) o c.c. — tartaric acid and 5 c.c. — KMnO^ colour disappears 
5 10 
after 
3'— 40" 
4'— 50" 
7'— 10'. 
