1129 
peroxide gradually separates metallie gold and that in light the 
change is markedly accelerated. 
The gold chloride solution used in these observations contains 1.8 
grams of metallic gold per litre of solution. 
As usual always blank experiments were made in darkness. The 
following table is formed from the mean of several observations 
carried out under exactly similar conditions. The temperature of 
experiments was 28° C. 
v 
= . . ~ . . . 
1) 5 ec. — oxalic acid and 5 e.e. gold chloride (containing 1.! 
10 j 
= 
grams cf gold per litre); reduction begins i.e. metallic gold appears after 
Sunlight Diffused light Darkness 
27" (seconds) 45! 65" 
(Deep-red coloured (Deep-red coloured (Yellow colour) 
particles) particles) 
N 
ZOMG Cc: Ti tartaric acid and 10 ¢.c. gold chloride; gold appears 
after 
Sunlight Diffused light Darkness 
8'— 56" 24 40 
N 
3) 10: ce. i citric acid and 10 ee. gold chloride; gold appears 
after 
Sunlieht Diffused lieht Darkness 
6'— 25" 20’ 45 
iN, : 
5) 10 ec. i malonie acid and 10 ee. gold chloride; gold appears 
after 
Sunlight Diffused light Darkness 
5'—10" 10; 17 
N 
OWN 7 formic acid and LO ce. gold chloride; gold appears 
after 
Sunlight Diffused light Darkness 
15’ 40) 95' 
7 
7) 10 cc. Th laetie acid and 10 ee. gold chloride; gold appears 
after 
Sunlight Diffused light Darkness 
30’ 85’ 180' 
13% 
