1356 
peroxide gradually separates metallic gold and that in light the 
change is markedly accelerated. 
The gold chloride solntion nsed in these observations eontains 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 ont ander exactly similar conditions. The temperature of 
experiments vcas 28° C. 
1) 5 c.c. — ^ oxalic acid and 5 c.c. gold chloride (containing 1.8 
grams of gold per litre) ; reduction begins i.e. metallic gold appearsafter 
Siinlight Diffused light Darkness 
27" (seconds) 45" 65" 
(Deep-red coloured (Deep-red c.oloured (Yellow colour) 
particles) particles) 
N 
2) 10 c.c. -- tartaric acid and 10 c.c. gold chloride ; gold appears 
after 
Sunlight 
8'— 56" 
N 
3) 10 c.c. — citric 
10 
after 
Sunlight 
6'— 25" 
iV 
5) 10 c.c. ^ malonic acid and 10 c.c. gold chloride ; gold appears 
after 
Sunlight Diffused light Darkness 
5'— 10" 10' 17' 
6) 10 c.c. — formic acid and 10 c.c. gold chloride; gold appears 
after 
Sunlight Diffused light Darkness 
15' 40' 95' 
77 
7) 10 c.c. — lactic acid and 10 c.c. gold chloride; gold appears 
after 
Diffused lighf Darkness 
24' 40' 
acid and 10 c.c. gold chloride; gold appears 
Dififused light Darkness 
20' 45' 
Sunlight 
30' 
Diffused light 
85' 
Darkness 
180' 
